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The reaction of an acid with a base is:

Is soil living or non living.

Which among the following is an artificial fibre?

Which if the following factors affect the growth of plants?

Which of the following method is used for obtaining silk fibres from cocoon?

the concept of photon was first given by .........

Q25. Consider the following statements about Water Scarce Cities Initiative:

1. It is one of the programs of World Bank.

2. Building resilience against climate change is one of the objectives of the initiative.

Which of the statements are correct?

What happens to blue litmus paper when it is dipped in vinegar?

Study the figure given and name the gas which is responsible for the formation of effervescence.

The variable coefficients d, e, f and g are considered for balancing the chemical equation. Relationships between these variable are constructed by balancing the atoms of each element on either side of the reaction. Which of the following are correct?

(Note: Coefficients should be natural numbers.)

(i) 2d= f, d = 3g and e= f + 2g

(ii) 2d = f, 3d = g and 2e = 2f + g

(iii) d = f2, 2d = g and e = 2f + 2g

(iv)d = 1, e = 3.5, f = 4 and g = 6

(v) d = 2, e = 7, f = 4 and g = 6

(vi) d = 2, e = 7, f = 3 and g = 4

Question 20

A mixture of iron nails, salt, oil and water is provided to you. Give stepwise methods to separate each component from this mixture?

${Al}_2{O}_3$ + $6HCl$ $\to$ $2Al{Cl}_3$ + $3H_{2}O$

${Al}_2{O}_3$ + $2NaOH$ $\to$ $2NaAl{O}_2$ + $H_{2}O$

(Sodium aluminate)

From the above reactions, you can conclude that _______.

Question 6

Pick from the following one chemical which is used to disinfect water.
(a) Chlorine
(b) Washing soda
(c) Silica
(d) Coal

There were some houses in Anu’s village which had no toilets and were too far to connect with a sewage system. So, government officials granted money under the Swachch Bharat Mission to construct eco-friendly, low water usage toilets that do not need a sewage system. Which of the following types of toilets could be constructed at a minimum cost?

State True or False. [3 MARKS]

a) Olfactory indicators respond to acid or base by change in smell.
b) When an aqueous solution of shampoo is mixed with the extract of red cabbage, the solution turns pink.
c) Methyl Orange is a natural Indicator.

Question 1 (b)
You must be familiar with the following nursery rhymes:
(i) ‘Baa baa black sheep, have you any wool.’
(ii) ‘Mary had a little lamb, whose fleece was white as snow

Answer the following:
(b) What is meant by the white fleece of the lamb?

What is the term used for explaining the separation of suspended materials with higher density to stick to the walls?

Karan took a beaker and mixed ink and water in it. Will he be able to separate ink and water using decantation process? Explain it. When can we use decantation?

The valency of nitrogen in $N_2$ molecule is:

Observe Figure 10.2 carefully and answer the following questions.

(a) Which process is being tested in the activity?
(b) What is the result of the activity? Give reasons.

Please explain me what is a valency

Why do you think air is transparent?

Ramya's science teacher said her reuse is better than recycling because:

Earth is known as the blue planet because 71% of the earth's surface is covered with water, but we still face water shortage. What can be the possible reason for this?

What happens to atmospheric pressure as the altitude increases?

Look at the table given below and fill in the blanks with correct word(s). [3 MARKS]

$\begin{array}{ccc}Properties& Acid& Base\\ RedLitmus& \left(i\right)\text{\_\_\_\_\_}& Turnstoblue\\ Taste& Sour& \left(ii\right)\text{\_\_\_\_\_}\\ Extractofredcabbage& \left(iii\right)\text{\_\_\_\_\_}& Turnstogreenishcolor\end{array}$

In which of the following states, the Brownian Motion is observed clearly?

1. 3

What is definition and use of salt in laboratory?

When an atom acquires the nearest noble gas configuration then why doesn’t it change into an atom of the noble gas

Mention the types of acids on the basis of their source? [2 MARKS]

Explain the following:

1) Galvanization

2) Crystallization [2 MARKS]

Why does a cooking gasbecome lighter after it has been used for few days?

According to Dobereiner's law of triads the number of elements present in each group is:

The ionic compound containing ${Ca}^{2+}$ and $(OH{)}^{-}$ would have the formula

Question 10

Forests are not responsible for
(a) providing medicinal plants
(b) maintaining the flow of water into the streams
(c) creating flood conditions
(d) absorbing rainwater and maintaining the water table

In winter we sometimes end up in fogging a mirror with our breath. Have you ever wandered what kind of change is that? After all the fog disappears after some time.

The chemicals used in the manufacturing of soap are

Which among the following non metals is in liquid form?

Which of these molecules are triatomic?

What happens to the chemical composition of the original substance during a chemical change?

Which of the following has a necessity of air?

Which of the following process is done just before straightening and rolling of the wool fibre?

Highly pure Hydrogen (~99.9% ) can be obtained from:

Which of the following is true about ozone?

A body floats or sinks in a liquid is due to the difference in their:

Which of the following is the empirical formula for the compound iron(II) carbonate?