Sound — Science STD 8 — Question

A key of mechanical piano is first struck gently and then struck again but much harder this time. In the second case:

In today's world, where water is a scarce resource, which among the following irrigation methods is most feasible and sustainable?

In human beings, after fertilization, the structure which gets embedded in the wall of the uterus is:

A musical instrument is producing a continuous note. This note cannot be heard by a person having a normal hearing range. This note must then be passing through:

Refer to the given figure showing different steps regarding antibodies fighting against a disease.

Arrange them in a correct sequence.

Electroscope is used to:

Assertion (A) Electrostatic force is a contact force.
Reason (R) The force exerted by a charged body on another charged body is known as electrostatic force.

Lightning conductor