1.
- convert 20g to kg
Correct Answer
D. 0.020kg
Explanation
To convert grams to kilograms, we divide the given value by 1000 since there are 1000 grams in a kilogram. Therefore, 20 grams is equal to 0.020 kilograms.
2.
2. convert 23 ml to liters
Correct Answer
A. 0.023L
Explanation
To convert milliliters to liters, you divide the given value by 1000. In this case, 23 milliliters divided by 1000 equals 0.023 liters. Therefore, the correct answer is 0.023L.
3.
3. convert 18 km to mm
Correct Answer
C. 18000000mm
Explanation
To convert kilometers to millimeters, you need to multiply the given value by 1000. In this case, 18 km is equal to 18,000 meters. Since there are 1000 millimeters in a meter, you multiply 18,000 by 1000, which gives you 18,000,000 millimeters. Therefore, the correct answer is 18,000,000mm.
4.
4. convert 88 kg to mg
Correct Answer
D. 88000000mg
Explanation
To convert from kilograms to milligrams, we need to multiply the given value by 1,000,000. Therefore, to convert 88 kg to mg, we need to multiply 88 by 1,000,000, which equals 88,000,000 mg. Hence, the correct answer is 88000000mg.
5.
5. convert 23.6 cm to mm
Correct Answer
B. 236mm
Explanation
To convert centimeters to millimeters, you need to multiply the value in centimeters by 10. In this case, 23.6 cm multiplied by 10 equals 236 mm. Therefore, the correct answer is 236mm.
6.
6. define matter
Correct Answer
C. Anything that have mass and occupy space
Explanation
The correct answer is "anything that have mass and occupy space." This definition accurately encompasses the concept of matter, which refers to anything that has both mass and occupies space. Matter can exist in various forms, including solid, liquid, or gas, and is composed of particles such as atoms and molecules. This definition captures the fundamental characteristics of matter and distinguishes it from other entities that do not possess mass or occupy space.
7.
7. name the three states of matter
Correct Answer
C. Solid, liqui, and gas
Explanation
The correct answer is solid, liquid, and gas. These are the three states of matter. Solids have a fixed shape and volume, liquids have a definite volume but take the shape of their container, and gases have neither a fixed shape nor volume. Protons, neutrons, and electrons are subatomic particles, not states of matter. Metals, non-metals, and metalloids are classifications of elements. Freezing, melting, and evaporation are physical processes that can occur in different states of matter.
8.
8. explain what happens to the molecules in matter when it is Heated
Correct Answer
C. Molecules move farther apart
Explanation
When matter is heated, the molecules gain energy and start moving faster. This increased kinetic energy causes the molecules to move farther apart from each other. As the temperature rises, the intermolecular forces weaken, allowing the molecules to spread out more, leading to an expansion of the substance. This phenomenon is observed in various states of matter, such as solids turning into liquids or liquids turning into gases when heated.
9.
9. What instruments do we use to measure volume
Correct Answer
B. Graduated cylinder
Explanation
A graduated cylinder is used to measure volume. It is a tall, narrow container with markings on the side that indicate different volume measurements. The markings allow for precise measurements of liquid volume. A thermometer measures temperature, a scale measures weight, and a ruler measures length, but none of these instruments are specifically designed to measure volume. Therefore, the correct instrument to measure volume is a graduated cylinder.
10.
10. What instruments do we use to measure mass
Correct Answer
D. Scale
Explanation
A scale is used to measure mass. It is a device that uses the force of gravity to determine the weight of an object, which is directly proportional to its mass. By placing an object on a scale, it provides a numerical value that represents the mass of the object. Graduated cylinders, thermometers, and beakers are not used to measure mass, but rather to measure volume and temperature.
11.
11. What instruments do we use to measure density
Correct Answer
D. Graduated cylinder and scale
Explanation
To measure density, we need to determine the mass and volume of an object. A graduated cylinder is used to measure the volume of a liquid or irregularly shaped solid. A scale is used to measure the mass of the object. Therefore, the correct answer is graduated cylinder and scale. A thermometer and stop watch are not used to measure density, and a ruler alone cannot accurately measure the volume of irregularly shaped objects.
12.
12. what SI unit is used to measure volume
Correct Answer
C. Liters
Explanation
The SI unit used to measure volume is liters. Volume is a measure of the amount of space occupied by an object or substance, and liters is the standard unit for measuring volume in the International System of Units (SI). It is commonly used to measure the volume of liquids and gases. Grams is a unit of mass, kilometer is a unit of length, and degrees Celsius is a unit of temperature, none of which are used to measure volume.
13.
13. properties that cannot be observed with the five senses are called
Correct Answer
A. Sub-microscopic properties
Explanation
Sub-microscopic properties refer to properties that are too small to be observed with the five senses. These properties are at a scale that is smaller than what our senses can detect, such as the behavior of particles at the atomic or molecular level. Macroscopic properties, on the other hand, can be observed with the five senses as they are at a larger scale. Physical properties are characteristics that can be observed or measured without changing the composition of a substance, while biological properties are specific to living organisms.
14.
14. a substance consisting of two elements chemically combined is known as
Correct Answer
D. Compound
Explanation
A substance consisting of two elements chemically combined is known as a compound. In a compound, the elements are bonded together in a fixed ratio and cannot be separated by physical means. Unlike mixtures, where the components can be present in varying proportions, compounds have specific chemical properties and formulas. Therefore, compound is the correct answer in this case.
15.
15. a mixture that separate into two visible phases is known as
Correct Answer
B. Heterogeneous mixture
Explanation
A heterogeneous mixture is a mixture that contains two or more visibly distinguishable phases or components. In this case, the mixture separates into two visible phases, indicating that it is not uniform throughout and therefore classified as a heterogeneous mixture.
16.
16. a postitive charge particle found in the nucleus is called
Correct Answer
B. Proton
Explanation
A positive charge particle found in the nucleus is called a proton. Protons have a positive charge and are one of the fundamental particles that make up an atom. They are located in the nucleus along with neutrons, which have no charge. Electrons, on the other hand, have a negative charge and orbit around the nucleus. Therefore, the correct answer is proton.
17.
17. a change from liquid to solid is called
Correct Answer
C. Freezing
Explanation
A change from liquid to solid is called freezing. Freezing occurs when the temperature of a substance is lowered below its freezing point, causing the molecules to slow down and arrange themselves into a solid structure. This process involves the release of heat energy. Melting, on the other hand, is the change from solid to liquid, while boiling refers to the change from liquid to gas. Condensation is the change from gas to liquid.
18.
18. a change from liquid to gas is known as
Correct Answer
D. Evaporation
Explanation
Evaporation is the correct answer because it refers to the process of a liquid changing into a gas. This occurs when the molecules of a liquid gain enough energy to escape from the surface and become vapor. Evaporation commonly happens at the boiling point of a substance, but it can also occur at lower temperatures.
19.
19. a change from gas to liquid is called
Correct Answer
D. Condensation
Explanation
Condensation is the process in which a substance changes from its gaseous state to its liquid state. This occurs when the temperature of the gas decreases, causing the particles to lose energy and come closer together, forming a liquid. Sublimation refers to the change from solid to gas without passing through the liquid state, evaporation is the process of a liquid turning into a gas, and freezing is the transformation from liquid to solid. Therefore, condensation is the correct answer for a change from gas to liquid.
20.
20. a mixture of sand and iron particles can be separated by
Correct Answer
B. Magnetism
Explanation
A mixture of sand and iron particles can be separated by magnetism because iron is a magnetic material, while sand is not. By using a magnet, the iron particles can be attracted and separated from the sand. This method takes advantage of the magnetic properties of the iron particles, allowing them to be easily separated from the non-magnetic sand particles.
21.
21. a mixture of salt and water can be separated by
Correct Answer
C. Crystalization
Explanation
A mixture of salt and water can be separated by crystallization. This process involves allowing the water to evaporate, leaving behind the salt crystals. As the water evaporates, the solute (salt) becomes less soluble in the solvent (water) and starts to form solid crystals. These crystals can then be collected and separated from the remaining liquid. This method is commonly used in industries to obtain pure salt from saltwater solutions.
22.
22. a mixture of sand and water can be separated by
Correct Answer
A. Filtration
Explanation
A mixture of sand and water can be separated by filtration. Filtration is a process that involves passing the mixture through a filter, which allows the liquid (water) to pass through while retaining the solid particles (sand). This separation method is based on the difference in particle size between the sand and water. The sand particles are too large to pass through the filter, so they are trapped, while the water flows through.
23.
23. a mixture of peroxide and water can be separated by
Correct Answer
D. Distilation
Explanation
Distillation is the process of separating a mixture by heating it to create vapor and then cooling the vapor to collect the separated components. In the case of a mixture of peroxide and water, distillation can be used because peroxide has a lower boiling point than water. By heating the mixture, the peroxide will vaporize first, and then it can be condensed and collected separately from the water. This method allows for the separation of the two components based on their different boiling points.
24.
24. Burning wood is an example of
Correct Answer
B. Chemical change
Explanation
Burning wood is an example of a chemical change because it involves a chemical reaction. When wood is burned, it undergoes a combustion reaction where it reacts with oxygen in the air to produce heat, light, carbon dioxide, and water vapor. This reaction results in the formation of new substances with different properties than the original wood. Therefore, burning wood is not just a change in physical state or appearance, but a transformation at the molecular level, making it a chemical change.
25.
25. baking cake is classified as
Correct Answer
B. Chemical change
Explanation
Baking a cake is classified as a chemical change because it involves a chemical reaction. During the baking process, the ingredients in the cake batter undergo a series of chemical reactions, such as the leavening agents reacting with heat to produce carbon dioxide gas, causing the cake to rise. Additionally, the proteins in the flour coagulate, the sugars caramelize, and the fats melt and combine with other ingredients to form a new substance with different properties than the original batter. These chemical reactions result in the formation of a cake, which is a completely different product from the original ingredients.
26.
26. melting candle wax is classified as
Correct Answer
A. pHysical change
Explanation
Melting candle wax is classified as a physical change because it does not involve a change in the chemical composition of the substance. During melting, the wax changes from a solid to a liquid state due to the application of heat. However, the molecules of the wax remain the same, only their arrangement and movement change. This means that the properties of the wax, such as its molecular structure and composition, remain unchanged. Therefore, melting candle wax is considered a physical change.
27.
27. disolving salt in water is classified as
Correct Answer
A. pHysical change
Explanation
Dissolving salt in water is classified as a physical change because it does not involve a chemical reaction. In this process, the salt molecules are dispersed throughout the water molecules, forming a solution. The chemical composition of the salt remains the same, only the physical state changes. The salt can be recovered by evaporating the water, further confirming that it is a physical change rather than a chemical one.
28.
28. breaking class is classified as
Correct Answer
A. pHysical change
Explanation
Breaking a class is classified as a physical change because it does not involve a change in the chemical composition of the material. The glass is still made up of the same molecules before and after it is broken. Only the physical arrangement of the molecules has changed. This is different from a chemical change, where new substances are formed with different chemical properties.
29.
29. rusting is classified as
Correct Answer
B. Chemical change
Explanation
Rusting is classified as a chemical change because it involves a chemical reaction between iron, oxygen, and water. When iron comes into contact with oxygen and moisture, it undergoes oxidation, forming iron oxide (rust). This process is irreversible and results in a change in the chemical composition of the iron. Therefore, rusting is considered a chemical change rather than a physical change.
30.
30. molecules in a solid are arranged as follows
Correct Answer
C. Packed together and can only vibrate
Explanation
The correct answer is "packed together and can only vibrate". In a solid, the molecules are tightly packed together and held in a fixed position by strong intermolecular forces. This arrangement restricts their movement to only vibrating in their positions. The molecules do not have the freedom to slide over each other or move from one place to another, as described in the other options.
31.
31. water is an example of
Correct Answer
A. Compound
Explanation
Water is an example of a compound because it is made up of two different elements, hydrogen and oxygen, chemically bonded together. In a compound, the elements combine in a fixed ratio and can only be separated by a chemical reaction. Water, with the chemical formula H2O, fits this description as it always contains two hydrogen atoms and one oxygen atom.
32.
32. water is composed of
Correct Answer
B. One atom of oxygen and two atoms of hydrogen
Explanation
Water is composed of one atom of oxygen and two atoms of hydrogen. This is because the chemical formula for water is H2O, which means that there are two hydrogen atoms bonded to one oxygen atom.
33.
33. In the periodic a group of family is described as
Correct Answer
C. Vertical columns
Explanation
The correct answer is "vertical columns" because in the periodic table, elements are arranged in columns called groups or families. Elements within the same group have similar chemical properties and the same number of valence electrons. These groups or families are arranged vertically, making the vertical columns the correct description for a group or family in the periodic table.
34.
34. period go from
Correct Answer
B. Left to right
Explanation
The period in a sentence typically goes from left to right. This means that it starts at the left side of the sentence and moves towards the right side. This is the standard convention in English writing.
35.
35. the symbol of magnesium is
Correct Answer
D. Mg
Explanation
The correct answer is Mg. The symbol for magnesium is Mg.
36.
36. the symbol of copper is
Correct Answer
B. Cu
Explanation
The correct answer is Cu. Copper is a chemical element with the symbol Cu, derived from the Latin word "cuprum." It is a soft, malleable, and ductile metal that is widely used in electrical wiring, plumbing, and various industrial applications. The symbol Cu is internationally recognized and used to represent copper in the periodic table and chemical equations.
37.
37. what is the name of the element with symbol Sr
Correct Answer
D. Strontium
Explanation
The correct answer is strontium. Strontium is an element with the symbol Sr on the periodic table. It is a soft, silver-white metal that is highly reactive and found in various minerals. Strontium is commonly used in the production of fireworks, as well as in the manufacturing of glass for cathode ray tubes.
38.
38. in what period does iodine belong to
Correct Answer
A. 5
39.
39. in what group does sulfur belong to
Correct Answer
D. 16
Explanation
Sulfur belongs to group 16 on the periodic table, also known as the chalcogens. Group 16 elements are characterized by having 6 valence electrons and include oxygen, sulfur, selenium, tellurium, and polonium. These elements have similar chemical properties and tend to form compounds with other elements by gaining or sharing electrons to complete their outer electron shell. Sulfur, in particular, is a nonmetal and is commonly found in various minerals and compounds, playing important roles in biological processes and industrial applications.
40.
40. an example of a transition element is
Correct Answer
B. Scandium
Explanation
Scandium is an example of a transition element because it is a d-block element that has partially filled d orbitals. Transition elements are characterized by their ability to form multiple oxidation states and exhibit a wide range of chemical reactivity. Scandium, with its atomic number 21, belongs to the transition metal series and possesses properties typical of transition elements such as high melting and boiling points, metallic luster, and the ability to form colored compounds.
41.
41. an example of alkali metal is
Correct Answer
A. K
Explanation
The correct answer is K because K represents the chemical symbol for potassium, which is an alkali metal. Alkali metals are found in Group 1 of the periodic table and are highly reactive. They have one valence electron and are known for their ability to easily lose this electron to form positive ions. Potassium is a soft, silvery-white metal that reacts violently with water. It is commonly found in nature and is an essential element for many biological processes.
42.
42. an example of a noble gas is
Correct Answer
C. Ne
Explanation
Neon (Ne) is an example of a noble gas. Noble gases are a group of elements that are very stable and do not readily react with other elements. They have a full outer electron shell, which makes them chemically inert. Neon is commonly used in advertising signs and lighting due to its bright orange-red glow when electrically charged. It is also used in cryogenic applications and as a coolant in certain scientific equipment.
43.
43. an example of a hallogen is
Correct Answer
C. Br
Explanation
Br is an example of a halogen because it belongs to the halogen group on the periodic table. Halogens are a group of highly reactive nonmetals that have seven valence electrons, making them one electron short of a full outer shell. They readily react with other elements to achieve a stable electron configuration. Br, also known as bromine, is a reddish-brown liquid at room temperature and is commonly used in disinfectants, flame retardants, and pharmaceuticals.
44.
44. the electron configuration of phosphorus is
Correct Answer
D. 2,8,5
Explanation
The electron configuration of an element represents the arrangement of electrons in its atomic orbitals. Phosphorus has an atomic number of 15, which means it has 15 electrons. The electron configuration of phosphorus is determined by filling up the atomic orbitals in order of increasing energy. The first two electrons go into the 1s orbital, the next two go into the 2s orbital, and the next six go into the 2p orbital. This gives us a total of ten electrons so far. The remaining five electrons go into the 3p orbital, resulting in the electron configuration of 2,8,5.
45.
45. electron in the outer shell is called
Correct Answer
C. Valence electron
Explanation
The electron in the outer shell of an atom is called a valence electron. Valence electrons are involved in the formation of chemical bonds and determine the reactivity and chemical properties of an element. They can be shared, transferred, or participate in bonding with other atoms. Therefore, the correct answer is "valence electron."
46.
How many valence electron are present in an oxygen atom
Correct Answer
C. 6
Explanation
An oxygen atom has 6 valence electrons. Valence electrons are the electrons in the outermost energy level of an atom, and they are responsible for the atom's chemical properties and ability to form bonds. Oxygen has 6 electrons in its outermost energy level, which is the second energy level. Therefore, the correct answer is 6.
47.
47. which of the following pair belong in the same group
Correct Answer
C. C, Ge
Explanation
Na and Ca belong in the same group because they are both alkali earth metals. Si and Al do not belong in the same group because Si is a metalloid while Al is a metal. C and Ge belong in the same group because they are both nonmetals. S and Cl belong in the same group because they are both nonmetals and halogens.
48.
48. Where are the most active metals located?
Correct Answer
B. Bottom left hand side
Explanation
The most active metals are located on the bottom left hand side of the periodic table. This is because these metals have a low ionization energy and are highly reactive. As you move from left to right across a period, the ionization energy generally increases, making the metals less reactive. However, as you move down a group, the ionization energy generally decreases, resulting in more reactive metals at the bottom left.
49.
49. As you go from left to right across a period, the atomic size
Correct Answer
B. Decreases
Explanation
increase in nuclear charge shrinks the atoms as we move from left to reigt
50.
50. As you travel down a group, the atomic size
Correct Answer
A. Increases
Explanation
because of increase in nuclear charge