1214 + Interview Questions in Chemistry in Class 8 Page 11 InterviewSolution

501.	Plum pudding atomic model was suggested by Rutherford.
Answer» ANSWER :F

Discussion

502.	Plastic articles are available in all possible shapes and sizes. Have you ever wondered how this is possible?
Answer» Answer :Plastic ARTICLES are AVAILABE in all possible shapes and sizes. This is possible because plastic can EASILY be moulded in any SHAPE.

Discussion

503.	Pinku and Rinku are TIME IIT-F students. They went to a jewellery shop with their mother. They were delightedto see the lustrous gold ornaments. Pinku peeped through the showcase to see a diamond necklace and total Rinku- Really, the glitterance of diamonds is incomparable to the lustre of gold ! Rinku complained that their chemisty teacher explained the lustre of metals in detail but didn't mention about diamonds at all. They both decided to ask their chemistry teacher the next day. What Explanation will the teacher give ?
Answer» Solution :Metals possess free electrons and on adsorption of light, these electrons undergo excitation and deexcitation. This gives metal their lustre. Diamond does not possess any free electrons. However, when light falls on it,the edges of diamond REFLECT light at a certain angle and this pehnomenon is called total INTERNAL reflection. This lead to the SPARKLING of diamond which is RESPONSIBLE for its unique position among all gemstones.

Discussion

504.	Pickles are not stored in steel or aluminium containers because
Answer» STEEL has chromium which is POISONOUS. aluminium TAKEN up oxygen from pickles and spoils it. pickles have acids which can corrode IRON and aluminium MAKING pickles poisonous. None of the above Answer :C

Discussion

505.	Photolysis comes under which type of chemical reaction? Explain it with an example.
Answer» Solution :DECOMPOSITION in the presence of SUNLIGHT (i) Type of reaction. (II) Nature of REACTANTS and PRODUCTS

Discussion

506.	Phosphorite rock when treated with phosphoric acid gives a fertilizer which is preferred to a fertiliser obtained from the same mineral on treatment with conc. sulphuric acid justify
Answer» Solution :(i) Composition of super PHOSPHATE of lime and TRIPLE phosphate. (ii) Composition of phosphorite rock. (iii) Pioducts formed when phosphorite rock istreated with `H_3PO_4` and `H_2SO_4` SEPARATELY (iv) Comparison of percentage of phosphorus in the products. (v) Comparison of soluble nature of the products.

Discussion

507.	Phosphor bronze is an alloy of
Answer» <P> P, Cu and SN P, Cu and Sb P, 7m and Sn P, Cu and As Solution :CHOICE (1)

Discussion

508.	Periodic changes are the ones which take place
Answer» very slowly very FAST SUDDENLY after FIXED INTERVAL of TIME Solution :after fixed interval of time

Discussion

509.	Perfect moulds can be made by using wrought iron but not by using molten copper. Give reasons.
Answer» Solution :(i) Generally DENSITY in a solid state is higher than that in a LIQUID state. (ii) Requisites for a good mould. (III) Comparison of the volumes on the SOLIDIFICATION of iron and copper.

Discussion

510.	Perform the following activity and learn for yourself. Take two cloth pieces of the same size, roughly half a metre aquare each. One of these should be from natural fibre.the other could be a synthetic fibre. You can take help of your parents in selecting these pieces. Soak the pieces in different mugs each containing the same amount of water. Take the pieces out of the containers after five minutes and spread them in the sun for a few minutes. Compare the volume of the water remaining in each container.Do synthetic fabrics soak less/more water than the natural fabrics? Do they take less/more time to dry?What does this activity tell you about the characteristics of the synthetic fabrics?Find out from your parents about the durability, cost and maintenance of these fabrics, compared to the natural fabrics.
Answer» ANSWER :Let US take a COTTON CLOTH (natural fibre) and socks (artificial/synthetic fibre).

Discussion

511.	Pb(NO_3)_2+Fe_2(SO_4)_3toFe(NO_3)_3+PbSO_4 Coefficients of lead sulphate and ferric nitrate in the balanced equation of above reaction are
Answer» 3,4 3,3 3,2 2,3 Answer :C

Discussion

512.	Passengers travelling in an aeroplane are advised not to carry fountain pens because at higher altitudes,
Answer» ink VAPOURIZES DUE to high EXTERNAL pressure. solidification of ink takes places due to very low external pressure. pressure within the tube is more than the external pressure and causes leakage of ink. pressure within the tube is LESSER than the external pressure and causes leakage of ink. Answer :C

Discussion

513.	Particles of matter in gaseous state have more kinetic energy than in solids.
Answer» ANSWER :T

Discussion

514.	Oxygen required. for the combustion of safety matches can be produced from"___________"
Answer» SOLUTION :`KClO_3`

Discussion

515.	Oxides that react with acids to form salts.
Answer» SOLUTION :METALLIC OXIDES

Discussion

516.	Oxides that react with both acids and bases are known as :
Answer» SOLUTION :AMPHOTERIC OXIDES

Discussion

517.	Oxides of sulphur and nitrogen produce __________.
Answer» ANSWER :A::C::D

Discussion

518.	Oxide of a metal on treatment with water produces hissing sound and energy.The product (Y) formed on treatment with hydrochloric acid gives a solid 'X'. ldentify the oxide, the product (Y) and X . Also write all the balanced chemical equations and calculate molecular masses of the oxide, the product (Y) and X .
Answer» Solution :Calcium oxide on treatment with water produces hissing sound and ENERGY. `CaO+H_2Oto underset("PRODUCT (Y)")(Ca(OH)_2)` `Ca(OH)_2+2HCltounderset((X))(caCl_2)+2H_2O` Molecular MASS of CaO `=40+16=56` Molecular mass of `Ca(OH)_2=40+2(17)=74` Molecular mass of `CaCl_2=40+2(35.5)=111`

Discussion

519.	Organise a debate in the school. Children may be given an option to role play as manufacturers of synthetic fabrics or those of fabrics from natural sources. They can then debate on the topic 'My Fabric is Superior'.
Answer» ANSWER :STUDENTS SHALL do themselves.

Discussion

520.	One of the ten most endangered rivers in the world is
Answer» Ganges Yamuna Nile Amazon ANSWER :A

Discussion

521.	One molecule of a binary acid contains two hydrogen atoms and a negative radical X. What will be the formula of the salts when it reacts with bases like M(OH),M(OH)_2and M(OH)_3?Explain with reasons.
Answer» Solution :(i) Formula of the BINARY ACID. (ii) Valency ofX. (iii) Valency of M in each CASE. (iv)DERIVATION of the formulae of salts PRODUCED

Discussion

522.	One atom of hydrogen combines with one atom of chlorine and so the valency of chlorine is ……………… .
Answer» ANSWER :1

Discussion

523.	On what basis are metals different from non-metals?
Answer» Answer :Metals are different from non-metals on the basis of PHYSICAL and CHEMICAL PROPERTY.

Discussion

524.	What are the different types of synthetic fibres?
Answer» Answer :The DIFFERENT TYPES of synthetic fibres differ from ONE ANOTHER on basis of their :(i) strength(ii) WATER absorbong capacity

Discussion

525.	On heating, the temperature of the melting solid
Answer» increases. decreases. remains constant. may increase or DECREASE depending upon the nature of the SOLID. SOLUTION :During melting the temperature of solid remains constant, as the external HEAT energy is utilised ot overcome the forces of attraction between the molecules.

Discussion

526.	On heating, camphor changes into vapour form. It is a following type a change.
Answer» temporary and IRREVERSIBLE temporary and CHEMICAL PHYSICAL and REVERSIBLE chemical and reversible Solution :physical and reversible

Discussion

527.	On decreasing the heat, the kinetic energy of particles also decreases.
Answer» ANSWER :T

Discussion

528.	why should anyone not wear polyester clothes while working in the kitchen?
Answer» Answer :Polyester clothes are made from synthetic (artificial) fibres which melt on HEATING. Hench, a person wearing polyester clothes should not work inthe KITCHEN because if the cloth CATCHES FIRE, the fabric melts and stick to the body.

Discussion

529.	Ocean acidification due to the siposal of industrial waste has a negative effect on oceanic calcifying organisms. Why ?
Answer» Solution :The disposal of the industrial wastes in the ocean increases the acidity of ocean WATER which demages the shells of the OCEANIC calcifying ORGANISM. Therefore their self protection SYSTEM becomes weaker.

Discussion

530.	Occurrence of an earthquake is a periodic change.
Answer» ANSWER :F

Discussion

531.	Number of electrons in this energy shell is the same as the number of electronsin the valence shell.
Answer» SOLUTION :L ENERGY SHELL

Discussion

532.	Nucleus contains the three subatomic particles: electrons, protons and neutrons.
Answer» ANSWER :F

Discussion

533.	Nuclear charge of an element B is twice that of A. If A has two completely filled orbits and L shell is its outermost orbit, find out atomic numbers of A and B.
Answer» SOLUTION :(i) CALCULATION of number of electrons in FIRST 2 shell. (ii) Calculation of atomic number of A (iii) Calculation of atomic number of B from A (IV) 10,20

Discussion

534.	Why does a block of plastic released under water come up to the surface of water?
Answer» ANSWER :No, all the PLASTIC ARTICLES cannot be BENT EASILY.

Discussion

535.	Non-metals usally form acidic oxides.
Answer» ANSWER :1

Discussion

536.	Non-metallic oxides can be acidic or neutral in nature.
Answer» ANSWER :T

Discussion

537.	Noble metals like gold and platinum are insoluble both in HCl and in HNO_3. But, they are soluble in aquaregia. Justify
Answer» Solution :(i) PRODUCT OBTAINED from the mixture HCl and `HNO_3` (ii) COMPOSITION oquuaregia. (iii) Reactivity of GOLD with aquaregia. (iv) Product formed

Discussion

538.	NO is an acidic oxide, while NO_(2) is a neutral oxide.
Answer» ANSWER :F

Discussion

539.	Nmae the areas in india where oil is found
Answer» Answer :In INDIA, oil is FOUND in the state of ASSAM, gujarat, mumbai high and in the river basins of GODAVARI and Krishna.

Discussion

540.	Nitrogen and oxygen react to produce nitric oxide. What is the weight of oxygen required to convert 4.9 g of nitrogen to nitric oxide ?
Answer» Solution :(i) LAW of definite proportions.ltBrgt (ii) Determination of the WEIGHT of NITROGEN and oxygen which combine to fonn nitric OXIDE. (iii) Calculation of the weight of oxygen from the weight of nitrogen given. (iv) 5.6 g

Discussion

541.	Nitric acid is colourless when freshly prepared. But, on long standing, it turns to yellow. How do you account for this?
Answer» SOLUTION :Decomposition of nitric acid (ii) EFFECT of LIGHT on `HNO_3` Effect of product FORMED on cold `HNO_3`

Discussion

542.	Nitric acid attacks all the metals except noble metals but the nature of products of same metal along with corresponding nitrates depends upon the concentration of HNO_3. Explain.
Answer» Solution : In conc. `HNO_3`, more number of `NO_3`ions are present per unit volume, these `NO_3` ions ACTS asoxidizinga gent. It GETS reduced to `NO_2` duet to , more production of OXYGEN. In casoefdilute `HNO_3` less number of `NO_3^+ ` Ions are present. So It gets reduced to mtrlc oxide

Discussion

543.	Nature of the products obtained by complete combustion of methane are
Answer» ACIDIC, BASIC acidic, NEUTRAL basic , neutral Both are neutral. ANSWER :B

Discussion

544.	Nanotubes are formed by fullerenes allotrope of carbon.
Answer» ANSWER :t

Discussion

545.	Name two metals which can be cut with knife.
Answer» ANSWER :Sodium and POTASSIUM are TWO metals which are soft and can be cut with KNIFE.

Discussion

546.	Name the unit in which the calorific value of a fuel is expressed.
Answer» ANSWER :The CALORIFIC value of a FUEL is EXPRESSED in the unit kilojoule PER kilogram (kJ/kg).

Discussion

547.	Name the technique shown in the figure.
Answer» SOLUTION :SEPARATING FUNNEL TECHNIQUE

Discussion

548.	Name the states of matter shown in (b) and (c) in the above figure.
Answer» SOLUTION :(B) is LIQUID (C) is GAS

Discussion

549.	Name the purest form of charcoal.
Answer» SOLUTION :SUGAR CHARCOAL.

Discussion

550.	Name the process involved in figures (a), (b) and (c).
Answer» SOLUTION :ROTTING

Discussion

Explore topic-wise InterviewSolutions in .

Plum pudding atomic model was suggested by Rutherford.

Plastic articles are available in all possible shapes and sizes. Have you ever wondered how this is possible?

Pickles are not stored in steel or aluminium containers because

Photolysis comes under which type of chemical reaction? Explain it with an example.

Phosphorite rock when treated with phosphoric acid gives a fertilizer which is preferred to a fertiliser obtained from the same mineral on treatment with conc. sulphuric acid justify

Phosphor bronze is an alloy of

Periodic changes are the ones which take place

Perfect moulds can be made by using wrought iron but not by using molten copper. Give reasons.

Pb(NO_3)_2+Fe_2(SO_4)_3toFe(NO_3)_3+PbSO_4 Coefficients of lead sulphate and ferric nitrate in the balanced equation of above reaction are

Passengers travelling in an aeroplane are advised not to carry fountain pens because at higher altitudes,

Particles of matter in gaseous state have more kinetic energy than in solids.

Oxygen required. for the combustion of safety matches can be produced from"___________"

Oxides that react with acids to form salts.

Oxides that react with both acids and bases are known as :

Oxides of sulphur and nitrogen produce __________.

Organise a debate in the school. Children may be given an option to role play as manufacturers of synthetic fabrics or those of fabrics from natural sources. They can then debate on the topic 'My Fabric is Superior'.

One of the ten most endangered rivers in the world is

One molecule of a binary acid contains two hydrogen atoms and a negative radical X. What will be the formula of the salts when it reacts with bases like M(OH),M(OH)_2and M(OH)_3?Explain with reasons.

One atom of hydrogen combines with one atom of chlorine and so the valency of chlorine is ……………… .

On what basis are metals different from non-metals?

What are the different types of synthetic fibres?

On heating, the temperature of the melting solid

On heating, camphor changes into vapour form. It is a following type a change.

On decreasing the heat, the kinetic energy of particles also decreases.

why should anyone not wear polyester clothes while working in the kitchen?

Ocean acidification due to the siposal of industrial waste has a negative effect on oceanic calcifying organisms. Why ?

Occurrence of an earthquake is a periodic change.

Number of electrons in this energy shell is the same as the number of electronsin the valence shell.

Nucleus contains the three subatomic particles: electrons, protons and neutrons.

Nuclear charge of an element B is twice that of A. If A has two completely filled orbits and L shell is its outermost orbit, find out atomic numbers of A and B.

Why does a block of plastic released under water come up to the surface of water?

Non-metals usally form acidic oxides.

Non-metallic oxides can be acidic or neutral in nature.

Noble metals like gold and platinum are insoluble both in HCl and in HNO_3. But, they are soluble in aquaregia. Justify

NO is an acidic oxide, while NO_(2) is a neutral oxide.

Nmae the areas in india where oil is found

Nitrogen and oxygen react to produce nitric oxide. What is the weight of oxygen required to convert 4.9 g of nitrogen to nitric oxide ?

Nitric acid is colourless when freshly prepared. But, on long standing, it turns to yellow. How do you account for this?

Nitric acid attacks all the metals except noble metals but the nature of products of same metal along with corresponding nitrates depends upon the concentration of HNO_3. Explain.

Nature of the products obtained by complete combustion of methane are

Nanotubes are formed by fullerenes allotrope of carbon.

Name two metals which can be cut with knife.

Name the unit in which the calorific value of a fuel is expressed.

Name the technique shown in the figure.

Name the states of matter shown in (b) and (c) in the above figure.

Name the purest form of charcoal.

Name the process involved in figures (a), (b) and (c).