Question

Choose the correct option for each of the following statement:
 $ 1). $ Which of the following is a covalent compound?
A. Sodium chloride B. Carbon tetrachloride C. magnesium chloride D. calcium chloride
 $ 2). $ The salt that undergoes photochemical decomposition is?
A. Copper sulphate B. zinc carbonate C. Lead bromide D. silver nitrate
 $ 3). $ What is the effect on sodium chloride solubility in water on increase in temperature?
 $ 4). $ A substance that does not contain water of crystallization?
A. Blue vitriol B. Common salt C. Glauber reagent D. Washing soda crystals.

Answer 1

Hint :Covalent character is determined by the difference in the electronegativities of two elements. The more the difference between electronegativity of the elements, the less is the covalent character and more is the ionic character.

Complete Step By Step Answer:
 $ 1). $ Among the given options – Sodium chloride, carbon tetrachloride, magnesium chloride and calcium chloride, look for the compound having least difference in the electronegativities of their atom.
  So our answer is carbon tetrachloride (as smaller the size of atom, the more electronegative is it)
In the periodic table, when we go down, electronegativity of element decreases and when we move from left to right electronegativity of element increases. )
 $ 2). $ Many salts of silver undergo photo oxidation easily. Thus our answer is Silver nitrate
Silver nitrate will undergo decomposition easily into its elements.
 $ 2AgN{O_3} + sunlight \to 2Ag + 2N{O_2} + {O_2} $
 $ 3). $ Since, we know that dissolution of sodium chloride in water is an endothermic process, so with the rise in temperature, the solubility of sodium chloride in water increases very sharply.
 $ 4). $ To know the molecules of water of crystallization – let’s first know their chemical formula
For blue vitriol - $ CuS{O_4}.5{H_2}O $
Washing soda - $ N{a_2}C{O_3}.10{H_2}O $
Glauber reagent - $ N{a_2}S{O_4}.10{H_2}O $
Sodium chloride - $ NaCl $
As, we can see from the chemical formula that sodium chloride does not contain water of crystallization. Hence the correct option is B i.e. $ NaCl $

Note :
Water of crystallization or the water of hydration is the water trapped inside the crystals. This water can be removed from the crystals by the physical processes such as heating.