• Chemistry - Section 1
46. 

The main chemical constituent of clay is

A. silicon oxide
B.

एल्यूमीनियम बोरोसिलिकेट 

C.

ज़ीइलाइट

D.

 एल्यूमीनियम सिलिकेट


47. 

The iron ore magnetite consists of

A. Fe2O3
B.

Fe3OH4

C.

FeCO3

D.

3Fe2O3 .. 3H2O


48. 

The mineral containing both magnesium and calcium is

A. magnesite
B.

केल्साइट

C.

कर्नालिते 

D.

डोलोमाइट 


49. 

The major constituent of air is

A. nitrogen
B.

कार्बन डाइआक्साइड

C.

ऑक्सीजन 

D.

ह्य्द्रोजन 


50. 

The ionisation energy of hydrogen atom in the ground state is x KJ. The energy required for an electron to jump from 2nd orbit to 3rd orbit is

A. 5x/36
B.

5x

C.

7.2 x

D.

x/6