Question

The difference of number of water molecules in gypsum and plaster of Paris is

A. $$\frac{5}{1}$$
B. $$2$$
C. $$\frac{1}{2}$$
D. $$1\frac{1}{2}$$  
Answer :   $$1\frac{1}{2}$$
Solution :
Gypsum is $$\,CaS{O_4}.2{H_2}O,$$   where as plaster of paris is $$\,CaS{O_4}\,\frac{1}{2}{H_2}O.$$
No. of water $$ = \left( {2 - \frac{1}{2}} \right) \to \frac{3}{2}\,{\text{or}}\,1\frac{1}{2}$$      molecules

Releted MCQ Question on
Inorganic Chemistry >> S - Block Elements

Releted Question 1

A substance absorbs $$C{O_2}$$  and voilently reacts with water. The substance is

A. $$CaC{O_3}$$
B. $$CaO$$
C. $${H_2}S{O_4}$$
D. $$ZnO$$
Releted Question 2

Calcium is obtained by

A. electrolysis of molten $$CaC{l_2}.$$
B. electrolysis of solution of $$CaC{l_2}$$  in water.
C. Reduction of $$CaC{l_2}$$  with carbon.
D. roasting of limestone.
Releted Question 3

A solution of sodium metal in liquid ammonia is strongly reducing due to the presence of

A. sodium atoms
B. sodium hydride
C. sodium amide
D. solvated electrons
Releted Question 4

The hydration energy of $$M{g^{ + + }}$$  is larger than that of :

A. $$A{l^{3 + }}$$
B. $$N{a^ + }$$
C. $$B{e^{ + + }}$$
D. $$M{g^{3 + }}$$

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S - Block Elements


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