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What is the most common way of expressing the concentration of a solution ?

Match the conversion in $ColumnI$ with the type(s) of reaction(s) given in $ColumnII$.
$$\begin{array}{cccc}& ColumnI& & ColumnII\\ A.& PbS⟶PbO& p.& Roasting\\ B.& CaC{O}_3⟶CaO& q.& Calcination\\ C.& ZnS⟶Zn& r.& Carbonreduction\\ D.& C{u}_{2}S⟶Cu& s.& Self-reduction\end{array}$$

Identify the correct formula of sodium sulphate.

$\begin{array}{cccc}& \text{Reaction Names}& & \text{Reactions}\\ \text{i}& \text{Displacement reaction}& & \text{A.}CaO+O_2\to 2Ca(OH{)}_2\\ \text{ii}& \text{Decomposition Reaction}& & \text{B.}Fe+Pb(N{O}_3{)}_2\to Fe(N{O}_3{)}_2+Pb\\ \text{iii}& \text{Redox Reaction}& & \text{C.}MgC{l}_2+Ca(OH{)}_2\to Mg(OH{)}_2+CaC{l}_2\\ \text{iv}& \text{Combination Reaction}& & \text{D.}KCl{O}_3\to 2KCl+3O_2\\ \text{v}& \text{Double Displacement Reaction}& & \text{E.}C{O}_2+H_2\to 2CO+H_{2}O\end{array}$

On heating diffusion becomes faster. Why?

A house wife wanted her house to be white washed. She bought 10 kg of quick lime from the market and dissolved in 30 litres of water. On adding lime to the water, she noticed that the water started boiling even when it was not being heated. Give reason for her observation. Write the corresponding equations and name the product formed. [3 MARKS]

A solution of a substance 'X' is used for white washing.
1. Name the substance 'X' and write its formula.
2. Write the reaction of the substance 'X' named in (i) above with water.[2 MARKS]

The name "hydrogen chloride" was given by

1. Why is water written as H²O and not written as OH²

Who were the founders of Panchatwa?

Your blood, when magnified, reveals different kinds of cells. Based on this information, your blood is an example of a:

Why bursting a balloon causes a lot of noise and how is it related to thunder?

Atoms and non-polar molecules are electrically:

If you take 4 balloons and fill one with $H_2$ gas, second one with $N_2$ gas, third one with $O_2$ gas and the last one with $C{l}_2$ gas. Then which balloon will rise the highest in the same time interval.

Lead nitrate reacts with potassium iodide to form a yellow precipitate of.

What is a neutralization reaction? Give two examples.

What is an electron, proton and neutron? [3 MARKS]

What is the catalyst used in the given reaction?

$2H_2{O}_2\to 2H_{2}O+O_2$

on hot summer days tyres of vehicle may burst why?

Which of the following suits the nature of characteristics of plasma and Bose-Einstein condensate (BEC)?

You are provided with a negatively charged gold leaf electroscope. State and explain what happens when an ebonite rod rubbed with fur is brought near the disc of electroscope?

Where is the sea water trapped in order to obtain common salt from it?

Which compound in the given options does not contain oxygen?

The positively charged and negatively charged ions are respectively called _______ and _______.

What is the pH of Milk of Lime?

The cause of periodicity of properties of elements is due to the repetition of similar:

A soft silver-white metal 'A' burns with a golden-yellow flame to give a yellow power 'B,' which on treatment with water gives a clear solution 'C'. The solution placed on $Al$ attacks this metal, liberating a gas 'D' forming a water-soluble compound 'E'. The metal 'A' dissolves in liquid $N{H}_3$ to form a deep-blue solution which is a good conductor and an excellent reducing agent. Identify 'C':

The atomic number for sodium is 11 and the atomic number for oxygen is 8. Based on this information find out the chemical formula for Sodium oxide?

Which scientist used X-ray diffraction experiments to classify the elements?

Matter is:

In a reaction, In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Which law is applicable in this case?

(a) Why does common salt get wet during the rainy season ?

(b) How can this impurity be removed ?

(c) Name a substance which changes the blue colour of copper sulphate crystals to white.

(d) Name two crystalline substances which do not contain water of crystallisation.

Name one solid, one liquid and one gaseous non-metal.

How was it shown that an atom has empty space?

In the figure given alongside :

(a) Name the shells denoted by A, B and C. Which shell has least energy ?

(b) Name X and state the charge on it.

(c) The above sketch is of ................ model of an atom.