Energy Change in Chemical Reaction

Q.

Give an example of a reaction where the following are involved:

(a) Evolution of heat

(b) Absorption of heat

(c) High pressure is required

Q.

Constant boiling mixtures are known as :

1. Distillators

2. Constant compounds

3. Azeotropes

4. Woulfes compounds

Q.

Which of the following is an exothermic process?

1. Melting of ice

2. Evaporation of water

3. Boiling of soup

4. Condensation of water vapour

Q.

Water and alcohol are _____________ liquids.

Q.

(a) What is a chemical reaction.

(b) State the condition necessary for a chemical change or a reaction to take place.

Q.

Solubility of a gas in a liquid______ with rise of temperature.

Q.

___________ is the method of separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points.

1. Distillation

2. Crystallisation

3. Filtration

4. Decomposition

Q.

The two metals involved in the galvanization process are

1. iron and copper

2. iron and zinc

3. zinc and copper

4. copper an aluminium

Q.

Give an example of a reaction where the following are involved

(a) Heat

(b) Light

(c) Electricity

(d) Close contact

(e) Solution

(f) Pressure

(g) Catalyst

Q.

Give reasons for the following observations with regard to Halls Heroults process.

Cryolite and fluorspar are added to pure alumina.

Q. What does copper sulphate dissociate into when electric current is passed through it ?

Q.

Match the item of column I to column II.

Column 1	Column 2
Cooling the molten iron	Melting
Camphor (s)$\to$Camphor (g)	Vaporisation
Dry air $\to$ Liquid air	Liquefaction
Sodium(s) $\to$Sodium(l)	Freezing
Ethanol to ethanol vapour	Sublimation

Q.

Mixing of which of the following pair of components involve significant energy change?

1. Sulphur, Water

2. Sulphur, Iron filings

3. Calcium carbonate, Sulphur

4. Potassium, Ice cold water

Q.

Define effervescence.

Q. A chemical change can be identified by change in colour of the substance.

1. True
2. False