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Which one of the following statements is wrong about gases?

(a) Give the general name of the class of compounds having the general formula $C_n{H}_{2n-2}.$ Write the name of the first member of this homologous series.
(b) The general formula of a homologous series of carbon compounds is $C_n{H}_{2n}.$ Write the molecular formulae of the second and fourth members of the series.
(c) Write the molecular formulae of the third and fifth members of homologous series of carbon compounds represented by the general formula $C_n{H}_{2n+2}$

The reaction in which energy is absorbed is called as a/an _____________.

What happens to the colour of bromine water when $S{O}_2$ is passed into the solution?

Match the following stages of contact process to the products formed.

Name the product formed when $C{l}_{2}and{H}_2$ produced during the electrolysis of brine are made to combine.

A solution truns blue litmus red. Its pH is likely to be :

(a) 7

(b) 5

(c) 8

(d) 14

Explain that the formation of magnesium chloride is a redox reaction.

Give reason for the need of classification of elements. [2 MARKS]

A proton and an electron are accelerated by the same potential difference. Let${\lambda }_e$ and ${\lambda }_p$ enote the de Broglie wavelengths of the electron and the proton respectively.

1.5 mol of $O_2$ combines with $Mg$ to form the oxide $MgO$. The mass of $Mg$ (at. mass 24) that has combined is:

What type of chemical bonds are present in a solid compound which has a high melting point, does not conduct electricity in the solid state but becomes a good conductor in the molten state?

Which one of the following property is generally not exhibited by ionic compounds?

(a) Solubility in water.

(b) Electrical conductivity in the solid state.

(c) High melting and boiling points.

(d) Electrical conductivity in the molten state.

What are alcohols ? Write names and formulae of first four members of alcohols family.

The gas A is used by most of the animals to obtain energy from food through the process of respiration. When A is acted upon by radiation X, it gets converted into another gas B which an allotrope of A but poisonous when inhaled. B forms a kind of layer C in the upper atmosphere which absorbs radiations X coming from a source Y and prevent them from reaching the earth. Some chemicals Z released from the various devices on the earth are destroying the layer C slowly. In fact, a hole has already been formed in layer C over the area D of the earth.

(a) What are the gases (i) A, and (ii) B? Write their molecular formulae.

(b) Name the layer C.

(c) What are (i) X, (ii) Y, and (iii) Z?

(d) Name the area D.

(e) Name any two human ailments which may be caused by X.

The mass of CaO that would be obtained by heating 20 kg of $90\%$ pure lime stone is:

I need your help.....

I will be writing an entrance exam and the syllabus includes even the concept of mole.....

1. Explain the concept of mole?

2. Calculations based on weight-weight ....

3. Weight-volume and Volume-volume relationship......

Also please help me out in getting some sample entrance exam papers........

Thanking you

Gauthami

What type of bonds is present in a water molecule? Draw the electron dot structure of waster $\left(H_{2}O\right)$.

Give reasons for the following:
Blue colour of copper sulphate solution is destroyed when iron filings are added to it.

How are the less reactive metals (which are quite low in the reactivity series) extracted? Explain with the help of an example.

Define a coordinate bond and give the conditions for its formation.

Which of these statements are true regarding diamonds?

Why is the gastric juice of mammals acidic?

Will the electrons of noble gases stop revolving around the nucleus show me a digramatic form of covalent bonding

You are conducting the Ammonia Fountain Experiment. You use blue litmus solution to perform the experiment. What will you observe as a result of this experiment?

Environmental balance is maintained by

(a) Explain why :

(i) All the elements of a group have similar chemical properties.

(ii) All the elements of a period have different chemical properties.

(b) The atomic radii of three elements X, Y and Z of a period of the periodic table are 186 pm, 104 pm and 143 pm respectively. Giving a reason, arrange these elements in the increasing order of atomic numbers in the period.

The constituents used in the manufacturing of different types of glasses are given below.

Silica(${\text{SiO}}_2$), Sodium Carbonate (${\text{Na}}_2{\text{CO}}_3$), Calcium Carbonate (${\text{CaCO}}_3$), Potassium Carbonate(${\text{K}}_2{\text{CO}}_3$), Boron Oxide (${\text{B}}_2{\text{O}}_3$), Alumina (${\text{Al}}_2{\text{O}}_3$) and Lead Oxide ($\text{PbO}$)

Choose the option/s that correctly matches the constituents and its use.

In order to obtain 1 tonner of aluminium, the following inputs are required. 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is Iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.

(a) When bauxite is treated with sodium hydroxide solution, what happens to:

(i) the aluminium oxide,

(ii) the iron (III) oxide?

(b) (i) Name the process used for the purification of bauxite.

(ii) Write the equation for the action of heat on aluminium hydroxide.

(c) (i) Write the formulae of cryolite.

(ii) Write down the word which correctly completes the following sentence.By dissolving aluminium oxide in cryolite a ..........(conducting/non conducting) solution is produced.

(iii) Why is so much graphite required for the electrolytic process?

(iv) Write the equation for the reaction which takes palace at cathode.

The non-metal A is an important constituent of our food and most of the fuels around us. A forms two oxides B and C. The oxide B is poisonous whereas oxide C cause global warming.

(a) Identify A, B and C.

(b) To which group of periodic table does A belong?

(c) Name another element which is placed in the same group as A.

Fresh milk has a pH of 6. When it changes into curd, the pH value will:

Reaction of copper with chlorine.formation of copper chloride

Which among the following elements has the tendency to form covalent compounds

Which method would not produce Ammonia gas?

When sodium hydroxide is added to calcium nitrate, the precipitate formed is of which colour?

Why are there gaps between hydrogen and helium and why can't they keep square blocks correctly?

What do you Mean by the term ' ionize'

Choose the correct option:

A lady is planning to white wash her house. She bought 10 kg of quicklime from the market and dissolved it in 30 litres of water. On adding lime in water she noticed that the water started boiling without being heated. Give reasons for her observation. Write the corresponding equations and name the products formed.

What is meant by the terms 'solute' and 'solvent'? Explain with examples.

What are planktons?

An element X of atomic number 12 combines with an element Y of atomic number 17 to form a compound $X{Y}_2$. State the nature of the chemical bond in $X{Y}_2$ and show how the electron configuration of X and Y change in the formation of this compound.

Which of the following are the amorphous allotropic forms of carbon?

The elements whose oxides can turn litmus solution blue are :

(a) Carbon and sulphur

(b) Sodium and carbon

(c) Potassium and magnesium

(d) Magnesium and sulphur

Chlorine gas evolves when HCl acid is added to: