Work And Energy — Science STD 9 — Question

One of the following elements has an atomicity of ‘one’. This element is:

1. Helium.
2. Hydrogen.
3. Sulphur.
4. Ozone.

If two solutions have the same concentrations, they are said to be:

A rigid body of mass m kg is lifted uniformly by a man to a height of one metre in 30 sec. Another man lifts the same mass to the same height in 60 sec. The work done on the body against gravitation in both the cases are in ratio:

Which statement about atom is incorrect?

Rhythmic contraction and relaxation throughout life, are shown by:

In water, the proportion of oxygen and hydrogen by mass is:

1. 1 : 4
2. 1 : 8
3. 4 : 1
4. 8 : 1

Which of the following statements is incorrect?

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.

Who believed that atoms could not be split: