<u>Answer:</u>
<em>B. A and B</em>
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<u>Explanation:</u>
1. Solids have a definite volume, definite size and definite shape
2. The particles present in a solid are very closely packed since the intermolecular forces between them are very strong. The molecules do not move apart.
3. Melting point is the temperature at which solid changes into a liquid.
4. When a solid is heated to the melting point the intermolecular forces are overcome by the energy and the molecules present in it moves from its fixed position to take its liquid state which is called as melting.
Answer:
31.345 cm³
Explanation:
Given:
Mass of the empty flask, m = 56.12 g
Mass of the flask filled with water, M = 87.39 g
Density of the water, ρ = 0.9976 g/cm³
now,
the mass of water filled in the flask, Mw = M - m = 87.39 - 56.12 = 31.27 g
also,
Density = mass / volume
thus, for water
0.9976 = 31.27 / volume
or
volume of water = 31.345 cm³
hence, the volume of flask is the volume of water filled = 31.345 cm³
Answer: Positive, positive
Explanation:
Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.
is positive when randomness increases and is negative when randomness decreases.
Exothermic reactions are defined as the reactions in which energy is released in the form of heat and 
for the reaction comes out to be negative.
Endothermic reactions are defined as the reactions in which energy is absorbed in the form of heat and for the reaction comes out to be positive.
For a cold pack, the energy has to be absorbed for the dissolution of ammonium nitrate in water so that the surroundings feel cold.Thus as energy is absorbed, for the reaction comes out to be positive.
The solid form of ammonium nitrate is getting converted to ions and thus entropy increases and thus for the reaction comes out to be positive.
Answer:
Heat
Explanation:
Energy exchange occurs when two systems exchange energy between them, or a system exchange energy with its surroundings. This phenomenon can happen in two ways: heat or work.
The heat is the exchange of energy caused by the difference in temperature. So, when the systems lose heat, its temperature decreases, and when it gains heat, its temperature increases.
The work is the energy exchange caused by the difference in volume and pressure. When a gas expands, its volumes increase, and it does work to its surroundings. When it compresses, its volumes decrease and it suffers work from its surroundings.
So, when the wax melt, the temperature of it must have increased, and it has gained heat. The energy exchange as heat.
