Haneet Gandhi and Yukti Sharma Solutions for Chapter: Materials Around Us, Exercise 2: PREVIOUS YEARS' QUESTIONS

When a copper plate is exposed to moist air for long, it acquires a dull green coating. The green material is:

Air is a mixture of many gases. The percentage by volume of the gases other than nitrogen and oxygen, that is, ${\mathrm{CO}}_2$, methane, argon, ozone and water vapour combined is about _____.

While teaching the topic on 'Motion and Time' to Class VII students, Savita gave examples of different kinds of motion to the students. Which one of the following examples was quoted incorrectly by her?

A rectangular container given below is filled with a liquid heavier than water:

Select the correct statement from the following about the liquid pressure.

Light is falling on the surface ${\mathrm{S}}_1, {\mathrm{S}}_2$ and ${\mathrm{S}}_3$ as shown below:

The surface(s) on which the angle of incidence is equal to the angle of reflection is/are:

The ultrasound equipment used for investigating medical problems works at frequency _____.

A solid rectangular block of iron is kept over the top of a table with its different faces touching the table. In different cases, the solid block exerts _____.

A boy has a thick paste of turmeric. On adding this paste to hydrochloric acid and an aqueous solution of sodium hydroxide separately, what colour(s) would he observe?