Structure of the Atom — Science STD 9 — Question

Lysosomes were discovered by:

The total force exerted by a body perpendicular to a surface is called.

The number of atoms in one mole of a substance is equal to ................?

Why does a ship made of steel float on water while an oil-pin of steel sinks down?

When an object is thrown up, the force of gravity.

_____ is the basic unit of life.

Which of the following is the largest phylum?

1. Arthropoda.
2. Ametida.
3. Mollusca.
4. Cnidaria.

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 of the following statements are true for pure substances?

1. Pure substances contain only one kind of particles.
2. Pure substances may be compounds or mixtures.
3. Pure substances have the same composition throughout.
4. Pure substances can be exemplified by all elements other than nickel.

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

Soil that is best suited for plant growth is:

1. Clayey.
2. Loam.
3. Sandy.
4. Gravel.