Crystals of Salts

Q.

Give reason :

(a) Silica gel pouches are kept in unused water bottles.

(b) Table salt becomes moist during rainy season.

(c) On opening a bottle of a cold drink, a fizz sound is heard.

Q.

What happens when SO₂ gas is passed through potassium dichromate solution?

1. Colour changes from orange to green
2. White precipitate forms
3. Colour changes from red to violet
4. Solution is decolourised

Q.

What do you observe when :

(a) Blue vitriol is heated ?

(b) Washing soda is exposed to air ?

(c) Blue litmus solution is added to water ?

Q.

Blue colored X changes to white colored Y on heating and in the presence of the moisture Y gives blue colored X. This is because ____

1. X is NaCl

2. X is the bleaching powder

3. X has some water of crystallization

4. None of the above

Q.

what is water of crystallization? write the common name and chemical formula of a commercially important compound which has ten water molecules a s water of crystallization. how is this compound obtained? write the chemical equation also. list any two uses of this compound.

Q.

Which method is used to separate sugar and water from its solution?

1. Centrifugation
2. Chromatography
3. Distillation
4. Separating funnel

Q. Which of the following compounds is known as epsom salt?

1. $CaS{O}_4\cdot 2H_{2}O$
2. $MgS{O}_4\cdot 7H_{2}O$
3. $M{g}_3(P{O}_4{)}_2$
4. $FeS{O}_4\cdot 7H_{2}O$

Q. Colour change of blue vitriole on heating is a:

1. chemical property of vitriole
2. physical property of vitriole
3. none
4. can't be predicted

Q. is a process that separates particles on the basis of difference in their densities.

1. Centrifugation
2. Sublimation
3. Chromatography

Q.

What is efflorescence?

Q.

State the colour of the following substances -:

• Silver chloride -
• Copper nitrate -
• Lead nitrate -
• Nitrogen dioxide-
• Silver bromide -
• Ferrous sulphate-