1214 + Interview Questions in Chemistry in Class 8 Page 5 InterviewSolution

201.	Two non-metal atoms contain same numberof electrons in their valence shells. One of the non-metal in its most abundant form react with the other non-metal forming a very stable compound 'A' . Compound 'A' on reaction with oxygen and fused sodium hydroxide gives tow products B and C. 'B' is used as raw material for the manufacture of glass and 'C' is the major constituents of glass. Identify A,B and C. Write balanced chemical eqations for the above reactions.
Answer» SOLUTION :(i) Raw material used in the manufacture of glass and the MAJOR constituents of glass. (II) Identification of B and C. (III) Identification of a based on the COMPOSITION of B and C.

Discussion

202.	What is teflon?
Answer» ANSWER :Teflon is a special type of plastic on which OIL and water do not STICK. It has an APPLICATION in COOKWARES.

Discussion

203.	What is therole of platinum in catalytic converter ?
Answer» SOLUTION :INCREASINGRATE of REACTION

Discussion

204.	Which metal is used to galvanize iron sheets?
Answer» COPPER ALUMINIUM Tin Zinc Answer :C::D

Discussion

205.	Which of the following metals on reaction with steam provides a coating over the metal and prevents further reaction ?
Answer» Al Ca Mg K Solution :Alumnium METAL on reaction with STEAM PROVIDES a COATING over the metal which PREVENT further reaction.

Discussion

206.	What are water pollutants?
Answer» ANSWER :The substances LIKE sewage, toxic chemicals, silt, etc. that pollute water are CALLED water POLLUTANTS.

Discussion

207.	What is meant by hardening is oils ? How is it done ?
Answer» Solution :CATALYTIC ADDITION of HYDROGEN some CARBON compounds

Discussion

208.	_________undergoes spontaneous combustion at room temperature.
Answer»

Discussion

209.	What happens when chlorine reacts with phosphorus
Answer» SOLUTION :`P_4 +6CL_2rarr4PCL_3,P_4+10CL_2rarr4PCL_5`

Discussion

210.	When Mg is burnt in the atmosphere of an element X white powder is obtained.When this is dissolved in water it gives a compoundY with pungent smell.What are X and Y?
Answer» <P>`C, CH_4` `N_2,NH_3` `P,PH_3` `S,H_2S` SOLUTION :CHOICE(2)

Discussion

211.	What is the role of atmosphere in nature?
Answer» SOLUTION :(i) Clouds (II) Rain (iii) Snow (IV) WINDS (V) Harmful raidations

Discussion

212.	What is meant by occlusion ? Give one example.
Answer» SOLUTION :The accomulation of MOLECULES of one COMPOUND over the SURFACE of ANOTHER compound .

Discussion

213.	Water of crystallization is a fixed amount of water present in the crystals of compounds.
Answer» ANSWER :t

Discussion

214.	Why are acid rains not confined to only industrial areas?
Answer» Solution :(i) PRESENCE of ACIDIC OXIDES (ii) DISSOLUTION of oxides

Discussion

215.	What is supernatantliquid?
Answer» SOLUTION :(i) CLEAR LIQUID FORMED (II) Solid-liquid solution

Discussion

216.	What is the valency ofnitrogen in ammonia? What is CAN? How is it useful?
Answer» SOLUTION : CALCIUM AMMONIUM NITRATE , FERTILIZER

Discussion

217.	What do you mean by water pollutants?
Answer» ANSWER :The substances that POLLUTE WATER are called water POLLUTANTS.

Discussion

218.	Which of the following metals is unsuitable for the preparation of hydratioi due to reversible reaction ?
Answer» Sodium Magnesium Copper IRON Solution :Iron is UNSUITABLE for the PREPARATION of hydrogen due to reversible REACTION.

Discussion

219.	Which of the following compounds is not associated with water molecules ?
Answer» BLUE vitrol Nitre Washing soda Epsom salt Answer :B::C

Discussion

220.	Water obtained from which source contains more minerals and why ?
Answer» Solution :(i) NATURE of SOLUTE (II) Nature of SOLVENT (iii) TEMPERATURE

Discussion

221.	What is non-biodegradable substance?
Answer» ANSWER :A material which is not EASILY DECOMPOSED by natural PROCESS is called non-biodegradable substance.

Discussion

222.	Washing soda is an example of a/an_____ substance .
Answer» efflorescent deliquescent hygroscopic Both (1) and (2) Solution :Washing SODA is an EXAMPLE of an efflorescent SUBSTANCE.

Discussion

223.	When a burning paraffin candle is introduced into two jars containing oxygen and chlorine gases separately, what observations can be made? Explain with appropriate reasons
Answer» Solution :(i) COMPOSITION ofparaffm candle and comparison of reactivity of the constituents present in candle with `O_2` and `Cl_2`. (ii) AFFINITY of the constituents ofparafi in candle towaids CHLORINE. (iii) Products obtained when these constituents react with chlorine. (iv) Physical STATES of the products. (v) Products obtained due to the reaction between constituents of paraffin candle and OXYGEN.

Discussion

224.	Two ice cubes can be joined by pressing them together and then by releasing pressure. How do you account for this?
Answer» Solution :(i) Effect of pressure on the MELTING POINT. (ii) CHANGES in the melting point of ice with pressure. (iii) The application of this is JOINING two ice cubes.

Discussion

225.	Write the effect of impurities and external pressure on the freezing point and boiling point of water. Explain with examples.
Answer» SOLUTION :(i) Vapour pressure (II) CHANGE INVOLVED

Discussion

226.	Which of the following pairs of oxides can give out oxygen on heating?
Answer» `MGO,PbO_(2)` `Na_(2)O,CaO` `K_(2)O,HgO` `Ag_(2)O,Pb_(3)O_(4)` Answer :A::D

Discussion

227.	The specific heat capacity of water is
Answer» `4.2 J KG^(-1)""^(@)C^(-1)` `4.2 J g^(-1)""^(@)C^(-1)` ` 1 J g^(-1)""^(@)C^(-1)` `1 J kg^(-1)""^(@)C^(-1)` SOLUTION :The SPECIFIC heat capacity of WATER is `4.2 J g^(-10) C^(-1)`

Discussion

228.	Where do you find the use of aluminium and copper wires? Have you seen wires of coal?
Answer» Answer :We can find aluminium and COPPER wires in the ELECTRICAL wire of the household electrification. No, we have not SEEN wires of COAL.

Discussion

229.	Write the balanced chemical reaction of the burning of ammonia in oxygen
Answer» SOLUTION :`4NH_3+3O_2rarr 2N_2+6H_2O`

Discussion

230.	What is the role of ultraviolet rays ip the purification of water in modern water purifiers?
Answer» Solution :(i) Oxygen REMAINS in the dissolved STATE in WATER. (ii)Conversion of oxygen to another allotropic form. (iii) Condition REQUIRED for the conversion. (iv)ROLE of that alltropic form in the purification of water.

Discussion

231.	Which of the following is not a physical change?
Answer» Dissolution of OXYGEN in water. Dissolution of carbon DIOXIDE in water. Dissolution of alcohol in water Dissolution of salt in water. Answer :B::C

Discussion

232.	When was nylon first made?
Answer» ANSWER :NYLON is the first fully synthetic FIBRE which is made from coal, WATER and air.

Discussion

233.	When phosphorus pentoxide reacts with water, the product is ______ .
Answer» SOLUTION :`H_(3)PO_(4)`

Discussion

234.	Vapour pressure of a liquid A is more that of B. Which of these liquids has higher crtical temperature in their gaseous state? Justify.
Answer» SOLUTION :(i) Relation between CRITICAL TEMPERATURE and intermolecular forces of attraction of a gas. (ii) Relation between vapour pressure on INTER molecular forces of attraction. (iii) Relation between inter molecular force of attraction and boiling point. (iv) Relation between boiling point and critical temperature.

Discussion

235.	What is the value of specific heat capacity of water ? How much heat energy is required to increase the temperatureof 5 grams ofwater to 1^(@)C ?
Answer» Solution :4.2 JOULE `G^(-1) ""^(@)c^(-1)`, 21 joule `g^(-1)""^(@)c^(-1)`

Discussion

236.	When a binary salt ofiron reactsw ith hydrochloric acid it gives out a gas which can be used for identification of many metal ions. Identify the salt, the gas and explain how it is usefill in detecting metal ions.
Answer» Solution :Gas used for DETECTION of IONS Identification of the gas, Balanced chemical equation. (iv) Identification of binary salt from the balanced chemical equation. (V) Reactivity ofmetal ions with the gas. (VI) PRODUCTS OBTAINED Colour of the product found

Discussion

237.	Which among the pair is separated by using the principle of dissolution in suitable solvent?
Answer» `SO_(2) and N_(2)O_(5),KOH` as solvent `SO_(2) and NO_(2),KOH` as solvent `SO_(2) and N_(2)O_(3), KOH` as solvent `SO_(2) and NO,KOH` as solvent Solution :DISSOLUTION in suitable solvent is ONE of the method of separation of gas - gas MIXTURE. As `SO_(2)` is acidic in nature it is DISSOLVED in basic KOH where as NO is neutral it does not dissolved in KOH. So `SO_(2)` and NO are deparated. From the solution `SO_(2)` is separated by chemical MEANS.

Discussion

238.	What is the relative mass of proton with respect to hydrogen atom ?
Answer» SOLUTION :NUMBER of PROTRONS in HYDROGEN

Discussion

239.	What are the observations of alpha-ray scattering experiment ? Based on thse obervations , how did Rutherford disprove Thomson's model ?
Answer» Solution :Observations : (i) Most of the `ALPHA`-particles passing STRAIGHT (ii) Large DEFLECTIONS

Discussion

240.	Tick true/false against the following statements. Coal tar is a mixture of various substances.
Answer» ANSWER :T

Discussion

241.	Two elements A, B have 14 and 8 electrons in M and N shells respectively. Then the ratio of their atomic numbers is
Answer» `2:3` `3:4` `3:2` `1:2` ANSWER :A

Discussion

242.	Water has maximum density at 4°C.
Answer» ANSWER :t

Discussion

243.	Which of the following reactions is associated with the formation of shining white globules?
Answer» `2HgOoverset(DELTA)to2Hg+O_(2)` `2Ag_(2)Ooverset(Delta)to4Ag+O_(2)` `2Pb_(3)O_(4)OVERSET(Delta)to6PbO+4O_(2)` `2NaNO_(3)overset(Delta)to2NaNO_(2)+O_(2)` SOLUTION :Silver (i) oxide on heating FORMS silvery white globules. `2Ag_(2)Oto4Ag+O_(2)`

Discussion

244.	What do you mean by sonorous?
Answer» ANSWER :The PROPERTY by virtue of which metals PRODUCE RINGING sounds when they are striked is called SONOROUS. For example, iron.

Discussion

245.	What is PET?
Answer» ANSWER :PET stands for Poly-Ester-Terylene. It is USED for making bottles, jars, utensils, FILMS, wires and other useful PRODUCTS.

Discussion

246.	What is the main advantage of the manufactring of oxygen gas by the electrolysis of water?
Answer» Solution :Comparatively low COST and `H_(2)` gas is obtained as a by PRODUCT.

Discussion

247.	Which postulate of Rutherford's theory is not derived from the results of alpha-ray scattering experiment ? On what basis Rutherford's could assume that ?
Answer» Solution :The postulate that the electrons REVOLVE round the nucleus is not derived from the results of `alpha`-ray scattering experiment . The results of `alpha`-ray scattering GAVE the idea that entire positive charge is concentrated in a small part which is known as nucleus. In ORDER of counterbalance the NUCLEAR forces of attraction , the electrons revolve round the nucleus at very high SPEEDS.

Discussion

248.	U.V rays find application in the purification of water, although it is harmful to human being. Explain.
Answer» Solution :U.V rays convets `O_(2)"to"O_(3)`. OZONE is used to purify DRINKING water as it PRODUCES nascent oxygen which kills the bacteria PRESENT in water.

Discussion

249.	What is potable water?
Answer» ANSWER :Water SUITABLE for DRINKING is CALLED POTABLE water.

Discussion

250.	Which of the following minerals does not contain oxygen?
Answer» SILICATES Carbonates PYRITES None of these Answer :C

Discussion

Explore topic-wise InterviewSolutions in .

What is teflon?

What is therole of platinum in catalytic converter ?

Which metal is used to galvanize iron sheets?

Which of the following metals on reaction with steam provides a coating over the metal and prevents further reaction ?

What are water pollutants?

What is meant by hardening is oils ? How is it done ?

_________undergoes spontaneous combustion at room temperature.

What happens when chlorine reacts with phosphorus

When Mg is burnt in the atmosphere of an element X white powder is obtained.When this is dissolved in water it gives a compoundY with pungent smell.What are X and Y?

What is the role of atmosphere in nature?

What is meant by occlusion ? Give one example.

Water of crystallization is a fixed amount of water present in the crystals of compounds.

Why are acid rains not confined to only industrial areas?

What is supernatantliquid?

What is the valency ofnitrogen in ammonia? What is CAN? How is it useful?

What do you mean by water pollutants?

Which of the following metals is unsuitable for the preparation of hydratioi due to reversible reaction ?

Which of the following compounds is not associated with water molecules ?

Water obtained from which source contains more minerals and why ?

What is non-biodegradable substance?

Washing soda is an example of a/an_____ substance .

When a burning paraffin candle is introduced into two jars containing oxygen and chlorine gases separately, what observations can be made? Explain with appropriate reasons

Two ice cubes can be joined by pressing them together and then by releasing pressure. How do you account for this?

Write the effect of impurities and external pressure on the freezing point and boiling point of water. Explain with examples.

Which of the following pairs of oxides can give out oxygen on heating?

The specific heat capacity of water is

Where do you find the use of aluminium and copper wires? Have you seen wires of coal?

Write the balanced chemical reaction of the burning of ammonia in oxygen

What is the role of ultraviolet rays ip the purification of water in modern water purifiers?

Which of the following is not a physical change?

When was nylon first made?

When phosphorus pentoxide reacts with water, the product is ______ .

Vapour pressure of a liquid A is more that of B. Which of these liquids has higher crtical temperature in their gaseous state? Justify.

What is the value of specific heat capacity of water ? How much heat energy is required to increase the temperatureof 5 grams ofwater to 1^(@)C ?

When a binary salt ofiron reactsw ith hydrochloric acid it gives out a gas which can be used for identification of many metal ions. Identify the salt, the gas and explain how it is usefill in detecting metal ions.

Which among the pair is separated by using the principle of dissolution in suitable solvent?

What is the relative mass of proton with respect to hydrogen atom ?

What are the observations of alpha-ray scattering experiment ? Based on thse obervations , how did Rutherford disprove Thomson's model ?

Tick true/false against the following statements. Coal tar is a mixture of various substances.

Two elements A, B have 14 and 8 electrons in M and N shells respectively. Then the ratio of their atomic numbers is

Water has maximum density at 4°C.

Which of the following reactions is associated with the formation of shining white globules?

What do you mean by sonorous?

What is PET?

What is the main advantage of the manufactring of oxygen gas by the electrolysis of water?

Which postulate of Rutherford's theory is not derived from the results of alpha-ray scattering experiment ? On what basis Rutherford's could assume that ?

U.V rays find application in the purification of water, although it is harmful to human being. Explain.

What is potable water?

Which of the following minerals does not contain oxygen?