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Which of the following is the correct interpretation of the given symbol?

$2H_2$

Why oxygen's symbol is red in colour ?

Why are thatched roofs of huts blown off during high winds?

A chemical reaction involves

During summer, Kavita carries water in a transparent plastic bottle to her school. One day, she left her bottle in the school. The bottle still had some water left in it. The following day, she observed some water droplets on the inner surface of the empty portion of the bottle. These droplets of water formed due to ____.

Ammonium nitrate is which type of salt

What is sandy soil

What is the difference between a food chain and a food web?

Choose the endemic fauna of the Pachmarhi biosphere reserve from the list below.

Which of the following is most suitable for the growth of plants?

What is the percentage of oxygen present in the earth’s atmosphere?

In Lavoisier's experiment what happened to the water of beaker?

What are the characteristics exhibited by a pure substance? [2 MARKS]

The pungent smell, when ammonium chloride is heated with sodium hydroxide solution, is due to the evolution of ___.

If a photosynthesizing plant releases oxygen containing more than the normal amount of ¹⁸O, it is concluded that the plant has been supplied with

1. C₆H₁₂O₆ containing ¹⁸O
2. H₂O containing ¹⁸O
3. CO₂ containing ¹⁸O
4. Oxygen in the form of ozone

Sir/mam what is pH value and what is it's full form?

Which of the following materials can be manufactured using polyester?

What is the importance of humus?

Which of the following are the products obtained from coal?
1) Coal tar
2) Petrol
3) Coal gas
4) Ammonical liquor
5) Paraffin wax
6) Coke

Due to change in which of the following properties matter can change from one state to another state?

Question 1

Which of the following serve as green lungs?
(a) Green pigment of the plants
(b) Forests
(c) Kitchen gardens
(d) Greenhouse gases

Which among the following formulae can be used for calculating the concentration?

(i)$\frac{\text{mass of solute}}{\text{mass of solution}}\times 100$

(ii) $\frac{\text{mass of solute}}{\text{mass of solute + solvent}}\times 100$

(iii)$\frac{\text{mass of solvent}}{\text{mass of solution}}\times 100$

(iv) $\frac{\text{mass of solvent}}{\text{mass of solute + solvent}}\times 100$

(v) $\frac{\text{mass of solute}}{\text{volume of solution}}\times 100$

(vi) $\frac{\text{mass of solvent}}{\text{volume of solution}}\times 100$

What are the reasons for the increase in the scarcity of freshwater? [5 MARKS]

Which of the following is the correct sequence of soil layers (starting from the surface) if a vertical profile of soil is taken?

Reason: Acid rain contains acids like nitric acids, which corrodes the upper layers of the buildings and monuments and damages them.

State whether the following statements are true or false. Correct the false statements. [5 MARKS]
(a) All substances are either acidic or basic.
(b) A compound if acidic will turn all indicators red.
(c) Lime water turns red litmus blue.
(d) Common salt dissolved in water turns blue litmus red.
(e) Phenolphthalein is a natural indicator.

How acidity of soil can be corrected?

Arrange solids, liquids and gases in ascending order of the intermolecular force of attraction.

Water contains Oxygen. Oxygen helps in burning. So why does not fire increases when we throw water at it?

Name the scientist who discovered the rayon

Some students of class 7 were taken for an educational trip to Waste water treatment plant .The teacher explained the process of water treatment. Identify the correct order of the process.

Step I:The liquid material is passed through sedimentation tank where solid waste like faecal matter, sand, grit settles down.

Step II:This solid matter is then removed with the help of a scrapper. This is the sludge.

Step III: Waste water is passed through bar screens to remove big objects like cans, sticks, rags etc.

Step IV: A skimmer removes the floatable solids like oil, grease etc.

Step V: Air is pumped into clarified water to help aerobic bacteria to grow. The bacteria then consume the unwanted matter still present in clarified water.

Step VI: The clear water so obtained is called clarified water.

Step VII:The suspended microbes settle at the bottom & the water is removed from the top.

What happens to blue litmus paper when you put it in vinegar?

State the type of the underlined phrase used in the sentence.

Gretchen went home and cooked food.

Which among the following is a common preservative?

Which of the following is true in the case of ice cream?

On what principle sublimation and chromatography is based

What is the silk covering over caterpillars known as?

Rearing of silk is followed by ______.

Which of the following does not deplete the water table at a place?

Question 2

Sewage is mainly a
(a) liquid waste
(b) solid waste
(c) gaseous waste
(d) a mixture of solid and gas

Match the entries in Column - I with those in Column - II

$\begin{array}{cccc}& \text{Column - I}& & \text{Column - II}\\ a.& \text{A chalk water}& 1& \text{A gaseous}\\ & \text{mixture}& & \text{mixture}\\ b.& \text{A glucose}& 2& \text{A heterogeneous}\\ & \text{solution}& & \text{solid-liquid mixture}\\ c.& \text{Carbonated}& 3& \text{A homogeneous}\\ & \text{water}& & \text{solid-liquid mixture}\\ d.& \text{Air}& 4.& \text{A gas-liquid mixture}\end{array}$

Which of the following can be used to control air pollution?

Which of the following is true about Suspended particulate matters?

We smell a pungent odour when there is an LPG leakage even though natural gas is odourless. Identify the proper reason for this smell.