Chemical Effects of Electric Current — Science STD 8 — Question

Metals are generally hard. Which of the following metals is an exception and can be cut with a knife?

Separating grains from chaff is called:

Naphthalene balls are used as:

Which one of the following is not a petroleum product?

Vaseline is made from?

The best technique of watering the fruit plants and trees is:

The semi-arid plains of a particular region show a pattern of alternating yellow and black stripes on the ground. The yellow stripes consist of land covered by ripening wheat. The black stripes are bare soil on which no crop is grown but farmers use herbicides or tillage to remove any weeds that try to grow in that region.
Why do farmers in this region manage soils in this way?

Which one of the following crops does not require nitrogenous fertiliser?