Control and Coordination — Science STD 10 — Question

Silver metal does not combine easily with oxygen but silver jewellery tarnishes after some time. How?

Platelets stop the blood at injury site by clotting it. How?

What happens when wood is burnt in a limited supply of oxygen? Name the residue left behind after the reaction and state two advantages of using this residue as a fuel over wood.

What is the shape of field lines inside a current-carrying solenoid? What does the pattern of field lines inside a current-carrying solenoid indicate?

Explain why, metals usually do not liberate hydrogen gas with dilute nitric acid.

Why any source of energy has less consequence? Explain your answer with suitable example.

Where is the magnetic field due to a straight current wire.

1. Stronger.
2. Weaker.

Give reason to justify the following:

1. The existence of decomposers is essential in a biosphere.
2. Flow of energy in a food chain is unidirectional.

Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.

Explain vegetative propagation with the help of two examples. List two advantages of vegetative propagation.