Efflorescence,Hygroscopy and Deliquescence

Q. Why is alum used in water purification?

Q.

Why is $AlC{l}_3$ soluble in water?

Q.

Table salt becomes sticky on exposure to humid air during the rainy season. Explain.

Q.

Explain the following with a suitable reason:

Washing soda loses its weight when exposed to atmosphere.

Q. The substances that loses the water of crystallization on exposure to dry air are called ________ substances.

1. efflorescent
2. deliquescent
3. crystalline
4. hygroscopic

Q. Calcium oxide is used as a drying agent because of its property called .

1. hygroscopy
2. deliquescence
3. efflorescence

Q. Why is alum used in water purification?

Q.

CuS$O_4$.5$H_2$O is white in colour.

1. True

2. False

Q.

In which of the following substances will there be :

(a) increase in mass

(b) decrease in mass

(c) no change in mass when they are exposed to air?

1. Sodium chloride

2. Iron

3. Conc. sulphuric acid

4. Table salt

5. Sodium carbonate crystals

Q.

Silica gel is desiccant

1. True
2. False

Q.

Which of the following absorb moisture from air:

1. Caustic soda

2. Soda ash

3. Glauber’s salt

4. Nitre

Q.

In which of the following substances can there be:

(a) increase in mass

(b) decrease in mass

(c) no change in mass

When exposed to air?

(1) Sodium chloride (2) Iron (3) Cone. sulphuric acid (4) Table salt (5) Sodium carbonate crystals

Q.

Why does table salt become sticky during the rainy season?

Q. The metal salt A is blue in colour. When salt A is heated strongly over a burner, substance B is eliminated, and a white powder C is left behind. When a few drops of liquid D are added to powder C, it becomes blue again. Identify A, B, C, and D.​

1. $A:{\mathrm{CuSO}}_4;B:{\mathrm{CuSO}}_4.5H_{2}O;C:H_{2}O;D:\mathrm{HCl}$
2. $A:{\mathrm{CuSO}}_4;B:{\mathrm{CuSO}}_4.5H2O;C:{\mathrm{CO}}_2;D:\mathrm{HCl}$
3. $A:{\mathrm{CuSO}}_4.5H_{2}O;B:H_{2}O;C:{\mathrm{CuSO}}_4;D:H_{2}O$
4. $A:{\mathrm{CuSO}}_4.5H_{2}O;B:{\mathrm{CO}}_2;C:{\mathrm{CuSO}}_4;D:H_{2}O$

Q.

Hard water is used to check_____.

Q.

Name a sharp smelling white solid that sublimes on heating and is an essential ingredient of ‘havan samagri’.

Q. Calcium oxide is used as a drying agent because of its property called .

1. hygroscopy
2. deliquescence
3. efflorescence

Q.

By giving example define the following terms: Water of crystallisation

Q. Which among the following categories of substances absorbs atmospheric moisture and forms a saturated solution?

1. Efflorescent substances
2. Deliquescent substances
3. Hygroscopic substances
4. Anhydrous substances

Q.

Explain, why table salt becomes sticky on exposure to humid air during the rainy season.

Q. Which of these are deliquescent salts?

1. $CaC{l}_2$
2. $MgC{l}_2$
3. $ZnC{l}_2$
4. $FeC{l}_3$
5. $K_{2}C{O}_3$
6. $NaN{O}_3$
7. $CaC{O}_3.2H_{2}O$
8. $CaO$

Q. What is meant by the water of crystallization?

Q. What are drying or desiccating agents? Give examples.​

Q.

In which of the following substances will there be :

(a) increase in mass (b) decrease in mass

(c) no change in mass when they are exposed to air?

1. Sodium chloride

2. Iron

3. Conc. sulphuric acid

4. Table salt

5. Sodium carbonate crystals

Q.

Q. Match the following substances with their corresponding properties.

1. Deliquescence
2. Efflorescence
3. Hygroscopy

Q. The substances that lose water on exposure to air are called ________ substances.

1. Desiccant
2. Deliquescent
3. Efflorescent
4. Hygroscopic

Q. Which of the following substances absorb moisture from air to form aqueous solution?

1. Hygroscopic
2. Deliquescent
3. Crystalline
4. Efflorescent