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Calculate the molecular mass of ${HNO}_3$ ?

The atomic number of an element Y is 17. The number of electrons in its ion $Y^{-}$ will be
(a) 17 (b) 18 (c) 19 (d) 20

Explain why :

(a) air is used to inflate tyres.

(b) steel is used to make railway lines.

A solution is prepared with 10 grams of solute in 100 grams of water. The mass percentage of the solution is ___%.

Which of the following is the chemical symbol for iron?

The mass per unit volume of a substance is called density. (Density = mass / volume). Arrange the following in order of increasing density.

Air, Exhaust from chimneys, Honey, Water, Chalk, Cotton and Iron. [3 MARKS]

Give the impact of acid rain :

(i) on plants

(ii) on soil

(iii) on water bodies.

Molecular mass of ammonia is __ gm.

Question 18
Arrange the following elements in the order of their increasing nonmetallic character
Li, O, C, Be, F
(a) F < O < C < Be < Li
(b) Li < Be < C < O< F
(c) F < O < C < Be < Li
(d) F < O < Be < C < Li

In beaker A, sugar cubes are dissolved into water while in beaker B, crushed cubes are taken. In which beaker, the rate of dissolution is faster and why? [2 MARKS]

The quantity of heat required to change a unit mass of a solid substance from the solid state to liquid state, while the temperature remains constant, is known as:

What is the chemical formula of Iron pyrite?

What is mixture and pure substance?

Which of the following arrangement of electrons do not represent Bohr’s model of an atom correctly?

Which of the following pairs are chemically dissimilar?

Which of the following will not under go disproportionation reaction in the presence of dilute (or) Conc NaOH

The pH of a solution is found to be 5.5. What is the nature of the solution?

Three isotopes of hydrogen are:

Which bond among the following has the shortest bond length?

Which one of the following elements is most reactive?

Mechanism of a hypothetical reaction $X_2+Y_2\to 2XY$ is given below
$I)X_2\rightleftharpoons X+X(fast\left)II\right)X+Y_2\to XY+Y\left(slow\right)III)X+Y\to XY(fast)$
The overall order of the reaction will be

What influence does an increase in reactant concentration have on the system which is in equilibrium?

Rain is called acid rain when its pH is below

Describe homogeneous, heterogeneous, suspension,colloid.

Which of the following symbols is approved by the IUPAC for copper?

Which one of the following methods is used to dry clothes in washing machine?

State the postulates of Dalton’s atomic theory. [5 MARKS]

In a chemical formula of a diatomic ionic compound, the valency of the anion is 3.Find out the valency of the cation.

Explain why a solution of salt in water is considered a mixture and not a compound.

Question 07.
A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish - orange. Which of the following would change the colour of this pH paper to greenish-blue ?

(a) Lemon juice
(b) Vinegar
(c) Common salt
(d) An antacid

Some salts while crystallising out from their solution, unite with a definite quantity of water which is known as _________.

Metals react with water to form metal oxide and _______ .

Locking of _______ and _______ free radicals is called scavenging.

Which of the following acids is not used in the preparation of hydrogen from metals?

What is mass number of an element? How is the mass number related to the protons and neutrons present in the nucleus of an atom?

When a beam of sunlight enters a room throuth a window, we can see tiny particles X suspended in a gas (or rather a mixture of gases )Y which are moving rapidly in a very haphazard manner.

(a) What could particles X be ?

(b) Name the gas (or mixture of gases) Y.

(c) What is the phenomenon exhibited by particles X known as ?

(d) What is causing the movement of particles X ?

(e) What conclusion doed the existence of this phenomenon give us about the nature of matter ?

Name one property of liquids and gases which tells us that therir molecules are moving constantly.

Which part of the Dalton's atomic theory came from the law of constant proportions given by Proust?

The isotopes of an element contain :

(a) same number of neutrons but different number of protons

(b) same number of neutrons but different number of electrons

(c) different number of protons as well as different number of neutrons

(d) different number of neutrons but same number of protons

In the following set of substances, one item does not belong to the set. Select this item and explain why it does not belong to the set :

Hydrogen, Oxygen, Steam, Chlorine