1.
Anything that is made up of two substances where the substances retain their identities.
Correct Answer
B. Mixture
Explanation
A mixture is a combination of two or more substances where each substance retains its own identity. In a mixture, the substances are physically combined and can be separated by physical means, such as filtration or distillation. This is different from a compound, where two or more elements chemically combine to form a new substance with different properties. Atoms, on the other hand, are the basic building blocks of matter and can exist as individual entities or combine to form molecules or compounds.
2.
A mixture that has the same composition throughout.
Correct Answer
A. Homogeneous
Explanation
The correct answer is homogeneous. Homogeneous refers to a mixture that has the same composition throughout. In other words, all the components of the mixture are evenly distributed and cannot be easily distinguished. This is in contrast to a heterogeneous mixture, where the components are not evenly distributed and can be easily distinguished.
3.
The composition is not uniform (iron and sand remain totally separated in the mixture).
Correct Answer
B. Hetrogeneous
Explanation
The given answer is "Heterogeneous" because the composition of the mixture is not uniform. It states that iron and sand remain totally separated in the mixture, indicating that the different components are not evenly distributed throughout. In a heterogeneous mixture, the individual substances can be easily distinguished and are not uniformly mixed together.
4.
A mixture of sand and salt
Correct Answer
A. Hetrogeneous
Explanation
The given mixture of sand and salt is heterogeneous because it contains two or more distinct components that are visibly different from each other. Sand and salt have different physical properties and can be easily distinguished by their appearance. In a homogeneous mixture, the components are evenly distributed and cannot be easily separated or distinguished. Therefore, the correct answer is heterogeneous.
5.
A cup of coffee with two sugars.
Correct Answer
B. Homogeneous
Explanation
The given answer, "Homogeneous," is correct because a cup of coffee with two sugars is a homogeneous mixture. In a homogeneous mixture, the components are evenly distributed and cannot be easily distinguished. In this case, the coffee and the two sugars are thoroughly mixed, resulting in a uniform composition throughout the cup.
6.
An alloy of copper and tin.
Correct Answer
A. Homogeneous
Explanation
The given answer is "Homogeneous" because an alloy of copper and tin is a mixture in which the copper and tin atoms are evenly distributed throughout the entire material. This means that the composition of the alloy is the same throughout, resulting in a uniform appearance and properties.
7.
A draw of black and grey socks.
Correct Answer
B. Hetrogeneous
Explanation
The draw of black and grey socks indicates that there are two different colors of socks in the draw. This suggests that the socks are not all the same, making the draw heterogeneous.
8.
A slice of pizza.
Correct Answer
B. Hetrogeneous
Explanation
A slice of pizza is considered heterogeneous because it is made up of multiple components that are easily distinguishable, such as the crust, sauce, cheese, and various toppings. Each of these components has different properties and characteristics, making the overall slice of pizza a mixture of different substances.
9.
A substance that cannot be broken down into any simpler structure.
Correct Answer
C. Element
Explanation
An element is a substance that cannot be broken down into any simpler structure. Elements are the building blocks of matter and are composed of atoms of the same type. Each element is uniquely defined by the number of protons in its atomic nucleus. Elements can combine with other elements to form compounds, but they cannot be broken down further by chemical means.
10.
__________ elements have been identified.
Correct Answer
A. 113
11.
Two or more elements joined chemically in fixed proportions.
Correct Answer
A. Compound
Explanation
A compound is formed when two or more elements combine chemically in fixed proportions. In a compound, the elements are bonded together in a specific arrangement, creating a new substance with different properties than the individual elements. Compounds can be represented by chemical formulas, which show the types and numbers of atoms present in the compound. This is different from atoms, which are the basic units of matter, and molecules, which are groups of atoms held together by chemical bonds.
12.
Compounds can only be separated into their pure components (elements) by _________ means.
Correct Answer
C. Chemical
Explanation
Compounds can only be separated into their pure components (elements) by chemical means. This is because compounds are formed by the chemical bonding of different elements, and breaking these bonds requires a chemical reaction. Physical methods such as filtration or distillation can only separate mixtures into their different components, but they cannot break down compounds into their elemental forms. Therefore, chemical means are necessary to separate compounds into their pure components.
13.
In this state of matter the particles making up the material are all packed close together and they touch one another.
Correct Answer
B. Solid
Explanation
Solid is the correct answer because in this state of matter, the particles making up the material are all packed close together and they touch one another. In a solid, the particles have a fixed position and vibrate in place. This close arrangement of particles gives solids a definite shape and volume.
14.
In this state of matter the particles making up the material are a little further apart but still are in contact with one another.
Correct Answer
A. Liquid
Explanation
In the state of matter known as liquid, the particles making up the material are a little further apart but still in contact with one another. This allows the material to flow and take the shape of its container. Liquids have a definite volume but not a definite shape. The particles in a liquid have more energy compared to those in a solid, which is why they are able to move around more freely.
15.
In this state of matter the particles making up the material are very far apart and have no contact with one another.
Correct Answer
C. Gas
Explanation
Gas is the correct answer because in the gas state of matter, the particles are widely spaced apart and have no contact with each other. The particles in a gas move freely and independently, filling the entire container they are in. Unlike solids and liquids, gases do not have a fixed shape or volume, as they can expand to fill any available space.
16.
Ice melts at ____________
Correct Answer
B. 0 celsius (0 fahrenheit)
Explanation
Ice melts at 0 degrees Celsius or 32 degrees Fahrenheit. This is the temperature at which ice changes from its solid state to a liquid state. At temperatures below 0 degrees Celsius, ice remains in its solid form, while at temperatures above 0 degrees Celsius, it starts to melt and become liquid water.
17.
Melting point of iron is ____________
Correct Answer
A. 1538 Celsius (2800 fahrenheit)
Explanation
The melting point of iron is 1538 Celsius (2800 Fahrenheit). This is the temperature at which iron transitions from a solid to a liquid state. At this temperature, the intermolecular forces holding the iron atoms together weaken and break, allowing the atoms to move more freely and take on a liquid form.
18.
Boiling point of iron is _____________.
Correct Answer
C. 2861 celsius (5182 fahrenheit)
Explanation
Iron has a boiling point of 2861 degrees Celsius (5182 degrees Fahrenheit). This means that at this temperature, iron changes from a liquid to a gas state. The high boiling point of iron is due to its strong metallic bonding, which requires a significant amount of energy to break the bonds between its atoms and allow it to vaporize.
19.
Melting point of mercury is ____________
Correct Answer
B. -38 celsius (-36 fahrenheit)
Explanation
Mercury has a very low melting point, which is why it is often used in thermometers. At -38 degrees Celsius (-36 degrees Fahrenheit), mercury changes from a solid to a liquid state. This low melting point allows it to easily expand and contract within the narrow tube of a thermometer, making it an ideal substance for measuring temperature.
20.
Boiling point of helium.
Correct Answer
A. -268 celsius (-450 fahrenheit)
Explanation
Helium has a very low boiling point, making it one of the coldest substances on Earth. At -268 degrees Celsius (-450 degrees Fahrenheit), helium transitions from a gas to a liquid state. This extremely low boiling point is due to the weak intermolecular forces between helium atoms, which require very little energy to overcome and cause the substance to boil.