1.
The temperature at which two or more than two types of crystals exist in equilibrium is called?
Correct Answer
B. Transition temperature
Explanation
The transition temperature refers to the temperature at which two or more types of crystals coexist in equilibrium. It is a point where a phase transition occurs, causing a change in the crystal structure. This temperature is significant as it marks the transition from one stable crystal form to another. It is different from the melting point, which is the temperature at which a substance changes from a solid to a liquid phase. The eutectic temperature is the lowest temperature at which a mixture of substances can exist as a liquid and is not relevant to this question. The boiling point is the temperature at which a substance changes from a liquid to a gas phase.
2.
The solid in which atoms, ions, or molecules have random non-repetitive three dimensional arrangements are termed as:
Correct Answer
B. Glasses
Explanation
Glasses are solids in which atoms, ions, or molecules have random non-repetitive three-dimensional arrangements. Unlike crystals, glasses do not have a regular repeating pattern. Instead, the arrangement of particles in glasses is disordered, giving them unique properties such as transparency and amorphous structure.
3.
Crystal lattice is the arrangement of particles in:
Correct Answer
C. Three dimensions
Explanation
Crystal lattice is the arrangement of particles in three dimensions because in a crystal lattice, particles are arranged in a repeating pattern in three perpendicular directions. This means that the arrangement extends in all three dimensions of length, width, and height. The particles are organized in a regular and symmetric manner, forming a three-dimensional network that repeats itself throughout the crystal structure. This arrangement allows for the characteristic properties of crystals, such as their geometric shapes and symmetry.
4.
The nature of bond in diamond is:
Correct Answer
B. Covalent
Explanation
Diamond is a form of carbon where each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement. Covalent bonds are formed by the sharing of electrons between atoms, resulting in a strong bond. In diamond, this covalent bonding extends throughout the entire crystal lattice, making it one of the hardest substances known. Therefore, the nature of the bond in diamond is covalent.
5.
Lattice energy is also called:
Correct Answer
A. Crystal energy
Explanation
Lattice energy refers to the energy released when ions come together to form a crystal lattice structure. It is also known as crystal energy because it specifically relates to the energy associated with the arrangement of ions in a crystal lattice. This energy is a result of the attractive forces between the oppositely charged ions in the lattice. It is different from ionization energy, which is the energy required to remove an electron from an atom or ion, energy of affinity, which is the energy released when an atom or ion gains an electron, and bond energy, which is the energy required to break a chemical bond.
6.
When gaseous ions are allowed to form a crystal, energy:
Correct Answer
A. Is evolved
Explanation
When gaseous ions are allowed to form a crystal, energy is evolved. This is because when gaseous ions come together to form a crystal lattice, they release energy in the form of lattice energy. This energy is released due to the attractive forces between the oppositely charged ions, which stabilize the crystal structure. Therefore, the process of forming a crystal from gaseous ions is exothermic, resulting in the evolution of energy.
7.
NaF and MgO have both atomic ratio 1:1 in their crystals such property is:
Correct Answer
B. IsomorpHism
Explanation
Isomorphism refers to the property of two or more substances having similar crystal structures and being able to substitute each other in a crystal lattice without disrupting its overall structure. In this case, NaF and MgO both have an atomic ratio of 1:1 in their crystals, indicating that they have a similar crystal structure and can substitute each other in the lattice. Therefore, the correct answer is isomorphism.
8.
Electric current can pass through graphite in one direction but not through other directions of crystal such property is called:
Correct Answer
B. Anisotropy
Explanation
Anisotropy refers to the property of a material where its physical or electrical properties vary depending on the direction. In the case of graphite, it exhibits anisotropy because electric current can pass through it in one direction (along the layers of carbon atoms) but not through other directions. This is due to the layered structure of graphite, which allows for easy movement of electrons within the layers but not between them. Therefore, anisotropy is the correct term to describe this property of graphite.
9.
Iron acts as an electrical conductor due to:
Correct Answer
A. Electron cloud
Explanation
Iron acts as an electrical conductor due to its electron cloud. The outermost energy level of iron atoms contains one or more loosely bound electrons that are not strongly attached to any particular atom. These free electrons are able to move through the lattice of iron atoms, creating a flow of electric current when a voltage is applied. This ability of iron to conduct electricity is essential for its use in electrical wiring, transformers, and other electrical devices.
10.
What method could be used to obtain copper from mixture of powdered copper and sodium chloride:
Correct Answer
D. Adding excess water to the mixture and filtering
11.
Lead and zinc can be separated by distillation because they have different:
Correct Answer
A. Boiling point
Explanation
Lead and zinc can be separated by distillation because they have different boiling points. Distillation is a process that involves heating a mixture to vaporize the more volatile component, which has a lower boiling point, and then condensing the vapor to obtain the purified substance. Since lead and zinc have different boiling points, they will vaporize at different temperatures, allowing for their separation through distillation.
12.
An insoluble solid was dropped into a measuring cylinder containing 50 cm3 of water. What will be the effect on volume of water?
Correct Answer
D. 65 cm3
Explanation
When an insoluble solid is dropped into a measuring cylinder containing water, the volume of water will increase due to the displacement of the solid. The solid will not dissolve in the water, but it will displace a certain amount of water, causing the volume to increase. Therefore, the effect on the volume of water will be an increase of 65 cm3.
13.
The spontaneous mixing of particles is called:
Correct Answer
C. Diffusion
Explanation
Diffusion refers to the spontaneous mixing of particles, such as molecules or ions, from an area of higher concentration to an area of lower concentration. This process occurs due to the random motion of particles. It is responsible for the spreading of odors in the air, the mixing of gases in the atmosphere, and the movement of substances across cell membranes. Evaporation involves the conversion of a liquid into a gas, sublimation refers to the direct conversion of a solid into a gas, and boiling is the rapid vaporization of a liquid. Therefore, diffusion is the correct answer as it specifically describes the spontaneous mixing of particles.