Tissues — Science STD 9 — Question

A radar signal is reflected by an aeroplane and is received in 2 × 10^-5s after it was sent. If the speed of these waves is 3 × 10⁸m/ s, how far is the aeroplane?

Identify the best definition of energy?

Which term can be used for the number of protons present in an atom?

Four elements W, X, Y and Z contain 8, 11, 9 and 17 protons per atom respectively. The element which cannot form an anion is most likely to be:

Application of nitrogenous manure to a plant causes.

Which of the following pair of elements represents a mole ratio of 1 : 1?

1. 10g of calcium and 12g of magnesium.
2. 12g of magnesium and 6g of carbon.
3. 12g of carbon and 20g of calcium.
4. 20g of sodium and 20g of calcium.

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.

Poultry farming is undertaken to raise following:

1. Egg production.
2. Feather production.
3. Chicken meat.
4. Milk production.

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

Work done by the gravitational force on a body of mass m moving on a smooth horizontal surface through a distance s is: (Given acceleration due to gravity =g):

A man is standing on a platform of a balance and takes a quick step, then his weight: