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The maximum number of electrons that can be accommodated in the outermost orbit is ___

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

What is the most common method of air separation?

Which of the following is/are incorrect about diamond?

When $NaHC{O}_3$ is heated, what is obtained?

Photosynthesis requires which of the following?

Statement 1: School bells are made up of graphite.
Statement 2: Non-metals are not sonorous.

(a) A magnesium ribbon is taken and burnt. The ash is then dissolved in water. Name the various products formed. Support your answer with reactions.

(b) Burning of wood and cutting it into small pieces are considered as two different types of changes. Explain.
[3 MARKS]

Identify the correctly matched pair

Which of the following elements has the least distance from nucleus to the outermost shell?

The lack of which of the following constituents of air forces us to breathe faster?

Pick the odd one out.

Question 21

Alist of jumbled words are given here. Write the correct form of each word
(a) WASHFERRET
(b) CHARREGE
(c) QUIFERA
(d) WOSN

When carbon dioxide is passed through lime water, it turns lime water _________

Why the pages in new books look white while those in older books turn yellow?

_{Why do we do shearing in summers?}

How do I find out if an atom is a element or compound?

In the following passage, there are ten blanks, each of which has been numbered. Against each, five words are suggested, one of which fits the blank appropriately. Find out the appropriate word in each case.

Twenty years (1)_______ now, nearly 60% of the world’s population will live in urban areas. The impact of urbanization might not all be positive in India as urban expansion is happening at a much (2)_______ rate than infrastructure expansion. Sustainability issues need to be (3)_______ so that economic development is not at the (4)_______ of public health. Some urban services that ought to be in (5)_______ in a city like water, electricity, transport etc. need special consideration. TERI has put together a detailed report that (6)_______ sustainability in the provision of basic urban services in Indian cities. (7)_______ public transport is a major reason for the proliferation of private vehicles on the road. Respiratory illness in children living in urban areas is on the (8)_______ with more cases of Asthma being (9)_______ because of pollution. The future of cities of Indian dreams depends on (10)_______ we can build better cities today.

Find out the appropriate word which fits the 8th blank.

Differentiate between melting and melting point

The picture below depicts interconversion between two states of matter. Identify the process 'X' by which gas is converted to liquid.

The process by which the woollen fleece of sheep is cut off with the thin layer of skin is known as

Difference between osmosis and diffusion

Which type of toilet is used in aeroplanes

Which among the following is not a natural habitat for conserving wildlife?

What is the purpose of chlorination in wastewater treatment? What are the various sources from which wastewater is generated? [3 MARKS]

What are endangered species? [1 MARKS]

Identify the element(s) having two electrons in the $\text{K}$ shell of its atom.

1. What is the next stage of the caterpillar?

Which of the following is homogeneous in nature?

[BHU 1981]

The phase change of a substance from the liquid state to the gaseous state is called __________

Which of the following is a reason for the decrease in the level of ground water?

Choose the correct statements in regard to salts from the following:

Statement 1: All salts are formed by the reaction of HCl and NaOH.

Statement 2: Salts are formed by the neutralization of acids and bases.

Statement 3: Salts are ionic compounds.

Statement 4: Salts are composed of cations and anions.

Statement 5: Salts are always white in colour.

Statement 6: NaCl is called as common salt.

Statement 7: pH of common salt is 7.

You are given two test tubes A and B, containing two different solution,one of them is an acidic solution and the other one is a basic solution. The solution in test tube B tastes sour while that in taste tube A is bitter in taste. You are asked to label the test tubes as acidic and basic. [2 MARKS]

Question 13.
To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is
(a) acidic
(b) neutral
(c) basic
(d) corrosive

Appu lives in an area where there is heavy rainfall. To prevent flooding of his village, the village has a parallel drainage system that collects rain water along with another drainage system that collects sewage. What is the drainage system that collects rainwater called?

Pasteurisation of milk is

When sufficient oxygen is not available, combustion of methane produces ______ gas and water.

What is the direct source of respiratory gas for a submerged aquatic plant?