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Plants take in oxygen and give out carbondieoxide during respiration all the time. why do we then say that plants supply oxygen to the air?

Question 2 (b)
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density

How to demagnetized a substance

Choose the most appropriate answer: Smog is mainly known as a mixture of fog and smoke. It

Teacher asked students not to use cracker this diwali because it produces many gases that pollute the environment. In your opinion burning of cracker is which kind of change?

The ground water level of a particular area increases if:

Air is not present in:

Which of the following is made using only a single type of material?

If we suspend a weight using a spring, as shown in the given figure -

What kind of changes are involved in this?

If a question is asked is this substance a conductor or insulator of electricity and we know almost all metals are condutor but plastic are insulator. But if we don't know is it a metal or a plastic then how we are going to answer such questions ?

When muddy water is kept for sometime undisturbed, impurities settle down. By which technique does the impurity settle down?

Why is it advised not to wear synthetic clothes while working in laboratory or kitchen? Name four synthetic fibres and mention their uses apart from their usage in clothes. [5 MARKS]

An example of irreversible change is:

Distinguish between solids liquid and gases on the basis of their following properties (a) compressibilty (b) fluidity (c) rigidity (d) expansion on heating

Question 13

Write any two activities which require less than bucket of water.

Two fishes had their home in the River Ganges. One day they were separated as they got flown away from home because of some natural calamity. Which type of natural calamity do you think is this?

Which of the following are the required conditions for rusting of iron?

Mention any three changes that take place in our body. [3 MARKS]

Which of the following is/are not a property of a base?

State any two effects of heat.

Which of the following statement is true?

Sarina was feeling thirsty but there was a pot of water at her home which was muddy and unfit to drink.How do you think Sarina would have made this water fit for drinking if the following materials were available to her?

alum. gas stove

Pan

Lid

Muslin cloth

Thread

Tub

In the list below indentify the mixture that you think can be separated.( one word)

A) Coffee powder in milk

B) Tea leaf suspended in a cup of tea

C) Assorted nuts

D) Butter and cheese

On lightning the candle, the candle burns and gives off light. Which of the following statement(s) about it is/are incorrect?

What are the different types of gases present in air and what is the percentage of the different gases which are present?

You are supposed to sort the materials given to you into groups. Which of the following can be in similar groups according to the materials used for making them?

Pen, barbie doll, apple, chair, bench, phone and shirt.

Difference between molecule and compound .With examples

Threshing technique to separate grains from stalk can be done using:

Fabrics are made up of ________ and yarns are made up of _______.

Which of the following are the methods used for separation of mixtures?

Question 9
Beera is a farmer. His field has black soil and the climate is warm. Which fibre yielding plant should he grow in his feild?
(a) Jute
(b) Cotton
(c) Coconut
(d) Wool

Name the separation method shown in diagram:

You are the captain of a ship and lost in ocean. You have finished all the drinking water storage. So ironically there is water everywhere but not any drop to drink. So how will you obtain fresh water to drink?

Which of the following option(s) always hold true for a change?

Group the following as reversible and irreversible changes:
1. Baking of potato
2. Making ice-cubes
3. Frying egg
4. Bursting balloon

Regarding the assertion and reason, choose the right option.
Assertion [A]: Green Revolution had certain toxic effects on the environment.
Reason [R]: High inputs of fertilizers and pesticides are very harmful for the environment.

When state is being changed from gas to liquid through process of condensation, temperature ___ .

Raj's house was under construction. During the construction, he saw a man removing pebbles and stones using a plastic mesh held in a frame.Which method of separation is used here? Explain it in detail while also mentioning examples. [3 MARKS]

Lump of cotton shrink in water because

A tap fills one half of a bottle in 1 minute. Three fourth of the remaining in next 1 minute. If the remaining volume is 7$m^3$ then find the volume of the bottle.
[4 MARKS]

Question 10

Catch water where it falls' is the basic idea behind

(a) recycling of water
(b) making dams to store water
(c) rainwater harvesting
(d) condensation of water vapour