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The increasing order of hardness of various kinds of coal is

The flame of a Kerosene on lamp (or lantern) has :

(a) single zone

(b) two zones

(c) three zones

(d) four zones

Match the entries of column I with column II
$$\begin{array}{cc}\text{Column A}& \text{Column B}\\ \text{(a) First artificial plastic}& \text{(i) Polythene}\\ \text{(b) First artificial fibre}& \text{(ii) DNA}\\ \text{(c) Biopolymer}& \text{(iii) Nylon}\\ \text{(d) Linear polymer}& \text{(iv) Bakelite}\end{array}$$

In a coffee machine, the ground coffee is separated from the coffee solution by using ___ .

A compound 'X' of sodium is commonly used in Kitchen for making crispy pakoras. It is also used for curing acidity in the stomach.
Identify 'X'. What is its chemical formula? State the reaction that takes place when it is heated during cooking.

___ is the second most important subtance on the Earth after air.

State four uses of hydrogen

Give one word / words for the following statements :

(a) Water fit for human consumption____________

(b) The harmful substances dissolved in water_______________

(c) The change of states of water from one form to another _____________________

(d) The gaseous form of water found in air _______________

(e) A mixture of common salt and ice _______________

(f) A substance which does not contain water __________________

(g) A property due to which a substance absorbs water without dissolving _______________

(h) Water molecules in loose chemical combination with other substances__________________

Draw the diagrams representing the atomic structures of the following :

(a) Nitrogen

(b) Neon

Silver article become black on prolonged exposure to air this is because

The pollutants released from oil refineries are ___ .

Which catalyst is used in the Bosch process when water gas is mixed with excess steam?

Melting of ice into water is a ___ (physical/chemical) change.

Which is the fuel that causes the least pollution

Subscripts in the chemical formula X₂Y₃ denotes:

A. 2 atoms of X combine with 3 atoms of Y to form X₂Y₃

B. The subscript 2 denotes that valency of X is 2.

What do you observe when

(a) Iron nail is kept in copper sulphate solution for sometime.

(b) Phenolphthalein is added to sodium hydroxidee solution.

(c) Blue litmus paper is dipped in dilute hydrochloric acid.

(d) Lead nitrate is heated.

(e) magnesium ribbon is burnt in oxygen.

(f)ammonia is brought in contact of hydrogen chloride gas.

Complete the following reaction.

Bio-degradable substances are materials that:

Which of the following is not a thermoplastic polymer ?

(a) polyester (b) melamine (c) nylon (d) polyvinyl chloride

When a vessel is exposed to moist air for a long time,then a green coating is formed on its surface.The vessel must be made of :

(a) zinc

(b) magnesium

(c) iron

(d) copper

The solubility of a salt at different temperatures is tabulated below:
$$\begin{array}{cccccc}\text{Temperature (degree celsius)}& \text{20}& \text{30}& \text{40}& \text{50}& \text{60}\\ \text{Solubility (g per 100 ml)}& \text{34.2}& \text{37.2}& \text{40.1}& \text{42.6}& \text{45.8}\end{array}$$

Deepti takes 50 ml of water and adds 20 g of salt to it. The temperature of the solution is ${20}^{\circ }$C. Choose the correct statement.

When you use air freshener, you spray it in one corner of the room and it spreads in the whole room very fast. This is because

The principle which is used to separate the cream from milk is __ .

If an atom of an element has 34 electrons in total, then what is the outer most orbit of the atom and the number of valence electrons?

Explain the chemical properties of metals.

Which one of the following fossil fuels is pumped from the ground rather than mining it?

Identify the bases from the following:

Which of the following measures will help to ensure the supply of clean water to the society?

Which gas makes a pop sound when burnt?

Explain why, we are advised not to sleep in a room having closed doors and windows, with a coal burning inside.

Tina is studying about polymers and was very surprised to know that everything is made up of polymers. So she started checking out the polymers of natural fibres, so what could be her result in the case of cotton?

When valve of an LPG cylinder is opened, which of the following reason allows the gas to flow to the burner?

Coal is a fossil fuel and it cannot be prepared in a laboratory or industry because the formation of coal:
A. Is a very slow process
B. Needs very low pressure and low temperature
C. Needs very high pressure and high temperature
D. Causes air pollution
Select the correct statement.

How is chlorination done to purify water?

In the given experiment, a mixture of methanol and ethanol is taken in a distillation flask. Which of the liquid component is obtained first after fractional distillation process?

What is the general name of the elements whose properties are intermediate between those of metals and non-metals ?

Give two examples for each of the following

(a) Metals

(b) Non-metals

(c) Metalloids

(d) Inert gases

In an overheated oil kitchen fire , Rohit 's mother put a lot of dry white powder 'X' on the pan. The fire got extinguished.

(A) What could be the dry powder 'X' ?

(B) How does 'X' extinguish the fire ?

( C) Name an another substance like 'X' used to extinguish fire.