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Which metal is used for:

(a) making pipes, buckets, water tanks,

(b) lithographic plates for printing,

(c) making face creams.

Which inert gas is used for filling electric bulbs so as to provide an inert atmosphere to the heating filament?

A reaction is given, which energy of activation for forward reaction is $\left(E_{af}\right)$ is $80kJmo{l}^{-1}$.Enthalpy change is $\Delta H=-40kJmo{l}^{-1}$ for the reaction. A catalyst lowers $E_{af}$ to $20kJ$$mo{l}^{-1}$.What will be the ratio of energy of activation for reverse reaction before and after addition of catalyst:

The reaction in which heat is liberated is called a/an _____________ reaction.

Question 1

Name any four different sources of water.

Identify the correct electronic configuration for ${\text{Mg}}^{2+}$ ion.

Why is it advised to rub baking soda at the body area bitten by an ant?

Which among the following is the correct formula of Glauber's salt?

Find gof
and fog, if

(i)

(ii)

Write two properties and two examples of acids.

Define combustion.

(i) Calculate
the number of electrons which will together weigh one gram.

(ii) Calculate the mass
and charge of one mole of electrons.

Helium accumulates in the earth’s crust through

Which of the following changes is a chemical change?

Give the Chemical formula for Sulphur dioxide

While $F{e}^{3+}$ is stable, $M{n}^{3+}$ is not stabe in acid solution because:
$(M{n}^{3+}+e^{-}\to M{n}^{2+},E^{\circ }=1.5V;O_2+4H^{+}+4e^{-}\to 2H_{2}O,E^{\circ }=+1.23V;F{e}^{3+}+e^{-}\to F{e}^{2+},E^{\circ }=0.77V)$

The solid residue obtained on the destructive distillation of wood is known as ___.

(a) A, B and C are the elements of a Dobereiner's triad. If the atomic mass of A is 7 and that of C is 39, what should be the atomic mass of B?

(b) Why was Dobereiner's triad discarded?

Write the importance of pH in our digestive system. What happens if excess acid is produced? How to neutralise it? [5 MARKS]

Which of the following option correctly represents the entries matched in column I and column II.

The chemical formula of common salt is

When we add water to milk, they get mixed properly because:

The process of freezing is an example of a physical change even though water and ice have different properties, why?

Two reversible heat engines A and B are arranged in series. A rejecting heat directly to B. Engine A receives 200 kJ at a temperature of 421 ${}^o$C from a hot source, while B is in communication with a cold sink at temperature 4.4${}^o$C. If the work output of A is twice that of B. The intermediate temperature between A and B is

Two positive ions, each carrying a charge q, are. separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be:

Question 8.

Why do the articles made of iron when placed in moist air get covered with reddish-brown, powdery substance? Is this process a physical or chemical change?

Pick the odd one out.