English Medium Class 9 - CBSE Question Bank Solutions for Science

A man is kidnapped, blindfolded and imprisoned in a big room. How could the man tell if he was in : a furnished room

An echo-sounder in a trawler (fishing boat) receives an echo from a shoal of fish 0.4 s  after it was sent. If the speed of sound in water is 1500 m/s, how deep is the shoal ?

The frequencies of four sound waves are given below. Which of these sound waves can be used to measure the depth of sea by the echo method ?

Which of the following device does not work on the multiple reflections of sound waves ?

State the number of atoms present in each of the following chemical species

`"CO"_3 ^ (2-)`

State the number of atoms present in each of the following chemical species

`"PO"_4 ^(3-)`

State the number of atoms present in each of the following chemical species

P₂O₅

State the number of atoms present in each of the following chemical species

CO

Verify by calculating that

1. 5 moles of CO₂ and 5 moles of H₂O do not have the same mass.
2. 240 g of calcium and 240 g magnesium elements have a mole ratio of 3 : 5.

In the Thomson’s model of atom, which of the following statments are correct?

1. the mass of the atom is assumed to be uniformaly distributed over the atom
2. the positive charge is assumed to be uniformaly distributed over the atom
3. the electrons are uniformaly distributed in the positively charged sphere
4.  the electrons attract each other to stabilise the atom

Organelle without a cell membrane is

Phloem transport ______ from ______ to other parts of the plant.

Salt can be recovered from its solution by evaporation. Suggest some other technique for the same?

Name the process associated with the following

An acetone bottle is left open and the bottle becomes empty.

Give an example of each mixture having the following characteristics. Suggest a suitable method to separate the components of this mixture

A volatile and a non-volatile component.

A rocket is moving up with a velocity v. If the velocity of this rocket is suddenly tripled, what will be the ratio of two kinetic energies?

Avinash can run with a speed of 8 m s^–1 against the frictional force of 10 N, and Kapil can move with a speed of 3 m s^–1 against the frictional force of 25 N. Who is more powerful and why?

A boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km he forgot the correct path at a roundabout (Fig. 11.1) of radius 100 m. However, he moves on the circular path for one and half-cycle and then he moves forward up to 2.0 km. Calculate the work done by him.

Can any object have mechanical energy even if its momentum is zero? Explain.

Can any object have momentum even if its mechanical energy is zero? Explain