Sound — Science STD 9 — Question

A rectangular wooden block has length, breadth and height of 50 cm, 25cm and 10cm, respectively. This wooden block is kept on ground in three different ways, turn by turn. Which of the following is the correct statement about the pressure exerted by this block on the ground?

1. The maximum pressure is exerted when the length and breadth form the base.
2. The maximum pressure is exerted when length and height form the base.
3. The maximum pressure is exerted when breadth and height form the base.
4. The minimum pressure is exerted when length and height form the base.

Which one of the following is a correct electronic configuration of sodium?

Tendency of a body to resist change in state of rest or motion is called:

Presence of tissues in a multicellular organisms ensures:

1. Faster development.
2. Division of labour.
3. Higher reproductive potential.
4. Body strength.

A student wants to have 3.011 × 10²³ atoms each of magnesium and carbon elements. For this purpose, he will have to weigh:

Simple tissues are these:

The substance which gives colloidal solution in water is:

Which of the following is the main difference between onion peel cells and human cheek cells?

Which of the following factors are responsible for the change in state of solid carbon dioxide when kept exposed to air?

1. Increase in pressure
2. Increase in temperature
3. Decrease in pressure
4. Decrease in temperature

1. (i) and (ii)
2. (i) and (iii)
3. (ii) and (iii)
4. (ii) and (iv)

Why do we weight less on moon as compared to earth ?