Weeds are the

1

(a)

main crop plants

(b)

insects and pests

(c)

unwanted plants growing along the crop

(d)

chemical substances

Planting of seeds is called

1

(a)

cultivation

(b)

irrigation

(c)

harvesting

(d)

sowing

Which of these do not have a regular cell structure?

1

(a)

Bacteria

(b)

Viruses

(c)

Protozoa

(d)

Algae

Which of the following is not a common property of plastics?

1

(a)

Non-reactive

(b)

Light in weight

(c)

Durable

(d)

Good conductor of electricity

The metal which produces hydrogen gas on reaction with dilute hydrochloric acid as well as sodium hydroxide solution is

1

(a)

copper

(b)

iron

(c)

aluminium

(d)

sodium

Petroleum was formed from organisms

1

(a)

living on the land

(b)

living on the plants

(c)

living in the sea

(d)

living on the rocks

Shyam was cooking potato curry on a chulha. To his surprise. he observed that the copper vessel was getting blackened from outside. It may be due to

1

(a)

proper combustion of fuel

(b)

improper cooking of potato curry

(c)

improper combustion of the fuel

(d)

burning of copper vessel

Which statement is incorrect about endangered species?

1

(a)

Their number has decreased drastically

(b)

They might become extinct in the near future

(c)

They pose a danger to other animals

(d)

Their natural habitat needs to be protected

Identify the correct statement.

1

(a)

Tissue is a group of dissimilar cells

(b)

An organ consists of similar cells

(c)

Vacuoles are not found in plant cells

(d)

Prokaryotes do not have nucleus

In humans, the development of fertilised egg takes place in the

1

(a)

ovary

(b)

testis

(c)

oviduct

(d)

uterus

The most conspicuous visible change that occurs in boys during puberty is

1

(a)

developmentin voice box

(b)

increase in height

(c)

production of sperms

(d)

increased sweating

Force due to the charged particles is known as

1

(a)

muscular force

(b)

magnetic force

(c)

electrostatic force

(d)

gravitational force

Some mustard oil is kept in the beaker. It will exert pressure

1

(a)

upward

(b)

downward

(c)

sideways

(d)

in all the directions

Rolling friction is smaller than

1

(a)

sliding friction

(b)

static friction

(c)

fluid friction

(d)

All of these

The loudness of sound depends on

1

(a)

its amplitude

(b)

its time period

(c)

its frequency

(d)

its speed

Where is the sprinkler water system useful?

2

(a)

Sprinkle water system is useful on the uneven land and at the land where water is not available. It is good for sandy soil.

Who increases the number of friendly microbes?

2

(a)

The loosened soil.

How is rayon formed?

2

(a)

Rayon is obtained by chemical treatment of wood pulp.

What happens when coal is heated in air?

2

(a)

When coal gets heated in air, it burns and produces mainly carbon dioxide gas.

What is biodiversity?

2

(a)

Biodiversity refers to the variety of organisms existing on the earth, their inter-relationships and relationships with the environment.

A cell in the human body that receives and transfers messages.

2

(a)

Nerve cell

Attraction or repulsion between objects is which type of force?

2

(a)

Magnetic

What are good conductors of electricity?

4

(a)

The materials that allow electric current to pass through them are called good conductors of electricity.

What are multiple images?

4

(a)

Images formed by mirrors placed at an angle to one another are called multiple images.

How are vehicles responsible for air pollution?

4

(a)

Vehicles produce high level of pollutants such as carbon monoxide, carbon dioxide, nitrogen oxide and smoke

How can a farmer increase the fertility of the soil?

4

(a)

How do some micro-organisms clean up the environment?

4

(a)

Complete the following chemical reaction. Sulphur dioxide SO₂ + Water (H₂ O) ⟶ Is it an acid/base?

4

(a)

Write briefly about Rock paintings.

4

(a)

What is weeding? Why is it necessary?

4

(a)

Why do plastic containers seem most convenient?

4

(a)

What is natural gas? What are the advantages of using CNG?

5

(a)

You have learnt the scientific facts about human reproduction. There are some myths and taboos regarding them. Explain few of them and discuss their solutions

5

(a)

What are food preservatives? Explain some common food preservatives.

5

(a)