A mixture of which one of the following pairs of gases is the cause of occurrence of most of the explosions in mines?

The most suitable crop for green manuring is

A. potato

B. sugarcane

C. sunhemp

D. gram

The advantage of detergents over soaps is

A. detergents are soluble in water

B. detergents could not givemuch lather

C. detergents give lather even with hard water

D. soaps give lather with only soft water

Consider the following features of newer models of motor cars.
1. Radial tyres
2. Streamlined body
3. Multipoint fuel injection
4. Catalytic converter with exhaust
Which of these features make the new models of motor cars more fuel efficient?

A. 1 and 2

B. 2 and 3

C. 2, 3 and 4

D. 1, 3 and 4

Bakelite is a co-polymer of phenol and

A. formaldehyde

B. acetaldehyde

C. benzaldehyde

D. cinnamaldehyde