An angle's measurement inradians is numerically equal to the length of a corresponding arc of a unit circle. One radian is just under 57.3 degrees.

Surface tension is measured in force per unit length. Its SI unit is newton per meter.

Projectile motion is a form of motion in which an object or particle is thrown near the earth's surface and it moves along a curved path under the action of gravity only.

The angular velocity is defined as the rate of change of angular displacement and is a vector quantity which specifies the angular speed of an object and the axis about which the object is rotating.

The image formed by a plane mirror is always virtual upright, and of the same shape and size as the object it is reflecting. A virtual imageis a copy of an object formed at the location from which the light rays appear to come.
So, the distance between the boy and his image = 5m + 5m =10m

A battery is a device that is able to store electrical energy in the form of chemical energy and convert that energy into electricity. The ions transport current through the electrolyte while the electrons flow in the external circuit and that’s what generates an electric current.

Electric fuse wire is an alloy made of tin (63 %) & lead (37 %).

The South Pole of the Earth's magnet is in the geographical North because it attracts the North Pole of the suspended magnet and vice versa.

Cathode rays (also called an electron beam or e-beam) are streams of electrons observed in vacuum tubes.Cathode rays are so named because they are emitted by the negative electrode or cathode in a vacuum tube. To release electrons into the tube, they first must be detached from the atoms of the cathode.
Hence option A is the right answer.

The hydrogen bomb eventually relies upon atomic fusion to release energy. Nuclear fusion is a nuclear reaction in which two or more atomic nuclei come very close and then collide at a very high speed and join to form a new type of atomic nucleus.