1214 + Interview Questions in Chemistry in Class 8 Page 9 InterviewSolution

401.	Temporary and reverisble changes are called ……….. Changes
Answer» SOLUTION :PHYSICAL

Discussion

402.	Tornado can be called a periodic change.
Answer» ANSWER :F

Discussion

403.	Talk to your parents or grandparents about the types of buckets that were used in the past. What is the material of the buckets or mugs you are using today? What are the advantages of using a plastic container?
Answer» Answer :The bucket used in the PAST were MOSTLY MADE of steel or iron any other METALLIC material ore wood.

Discussion

404.	Take a 250 mf, beaker /glass tumbler. Fill half of it with water. Now carefully cut asmall piece of sodium metal. Dry it using filter paper and wrap it in a small piece of cotton. Put the sodium piece wrapped in cotton into the beaker. Observe carefully '(During observation keep away from the beaker). When reaction stops touch the beaker. What do you feel? Has the beaker become hot? Test the solution with red and blue litmus papers. Is the solution acidic or basic?
Answer» Answer :Yes, the beaker thins HOT. We will find the solution to be BASIC after TESTING the solution with red and blue LITMUS papers.

Discussion

405.	Symbolic representation of an element.
Answer» SOLUTION :CHEMICAL SYMBOL

Discussion

406.	Symbolic expression for a molecule is called ………………. .
Answer» SOLUTION :CHEMICAL FORMULA

Discussion

407.	Symbolic representation of a chemical reaction.
Answer» SOLUTION :CHEMICAL EQUATION

Discussion

408.	Suppose you have two boxes similar in appearance, one made of wood and the othermade of metal. Can you tell which boa is made of metal by striking both the boxes?
Answer» Answer :By striking the boxes if we HEAR a SONOROUS sound, then it is a METALLIC BOX and if no sonoroussound is produced, then it is a wooden box.

Discussion

409.	Sulphur, on heating follows Which of the following sequence?
Answer» solid `rarr` THICK viscous liquid `rarr` thin liquid`rarr`gas solid`rarr` SEMI solid `rarr` liquid `rarr`gas solid`rarr` thin liquid `rarr` thick viscous`rarr`thin'liquid `rarr` gas solid`rarr`POWDERY solid`rarr`thick viscous liquid`rarr`gas SOLUTION :Choice (3)

Discussion

410.	Sulphur on reaction with HNO_3 gives "__________"
Answer» `H_2SO_4,NO_2,H_2O` `H_2SO_3,NO_2,H_2O` `H_2SO_4, NO,H_2O` `H_2SO_3,NO,H_2O` SOLUTION :`S+6HNO_3rarrH_2SO_4+6NO_2+2H_2O`

Discussion

411.	Sugar on reaction with _______ gives sugar charcoal.
Answer» ANSWER :CONC. `H_(2)SO_(4)`

Discussion

412.	Sugar, on being treated withH_2SO_4, forms a black residue. If we observe the weights of sugar and the residue, we find a difference m weights. Why?
Answer» Solution :(i) Sugar undergoes chemical change. (ii)Dlack CARBON residue is FORMED. (III) Sugar is a COMBINATION of carbon, HYDROGEN and oxygen.

Discussion

413.	Sugar is a ................. . (mixture/compound)
Answer» SOLUTION :COMPOUND

Discussion

414.	Sugar charcoal is good reducing agents.
Answer» ANSWER :TRUE

Discussion

415.	Substances with different densities can be separated by
Answer» filtration decantation centrifugation winnowing Answer :C

Discussion

416.	Substance with low ________ can catch fire easily.
Answer» ANSWER :A

Discussion

417.	Substance used in the preparation of carbon dioxide along with dil. HCl
Answer» ANSWER :MARBLE `(CaCO_(3))^(INFTY)`

Discussion

418.	Substance formed by burning of wood in limited oxygen.
Answer» ANSWER :CARBON MONOXIDE

Discussion

419.	Sublimation is a chemical change
Answer» ANSWER :F

Discussion

420.	Sublimation is a change in a substance from .............. state to...... State.
Answer» SOLUTION :SOLID, GASEOUS

Discussion

421.	Study the following graph and based on that answer the questions with suitable reason. The graph represents the various stages inveolved in step wise change of ice to steam. (a) Identify the stages associated with increase in temperature. Give reason. (b) In which stages, the temperature is constant? Why?
Answer» SOLUTION :(a) In the GRAPH, part 1 to 2,3 to 4 and 5 to 6 show heating of solid, liquid and gas respectively which increaseskinetic energy and hence there is rise in temperature. (b) the parts, 2 to 3 and 4 to 5 REPRESENT melting of solid and boiling of liquid. At these points the heat energy supplied is utilized for decreasing the INTERMOLECULAR force of attraction and hence there is no change in temperature

Discussion

422.	Stibnum is the Latin name of__________ .
Answer» SOLUTION :ANTIMONY

Discussion

423.	Steps involved in the Frasch process are given below. Arrange them in the correct sequence , Three melts the sulphur below melting point The sulphur foam formed rises in the middle pipe and is collected. Surerheated steam under pressure is sent through the outermost pipe Hot compressed air is sent through the innermost pipe , which froth up the molten sulphur below Three concentric pipes are drilled through the ground to the sulphur deposits
Answer» e c a d b e a d c b e a d b c e d a c b Solution :(i) Three CONCENTRIC PIPES are drilled through the GROUND to the sulphur deposits. (ii) Superheated steam under pressure is sent through the outermost pipe. (III)This melts the sulphur below melting point Hot compressed AIR is sent through the innermost pipe, which froths up the MOLTEN sulphur below. (V) The sulphur foam formed rises in the middle pipe and is collected

Discussion

424.	"Steam at 100^(@)C causes more burnswhen exposed ot skin than water at 100^(@)C ". Justify.
Answer» SOLUTION :(i) Change of state of MATTER. (ii) ENERGY content of water molecules at `100^(@)C` . (III) Energy content of steam molecules at `100^(@)C`. (iv) Comparision of energy .

Discussion

425.	State whther the following statement is true or false : Fabrics are made from fibres obtained from natural or artificial sources.
Answer» ANSWER :1

Discussion

426.	State whether the following statements are true or false There are no more than 94 naturally occurring element.
Answer» ANSWER :1

Discussion

427.	State whether the following statements are true or false Oxides of non-metals are acidic in nature.
Answer» ANSWER :1

Discussion

428.	State whether the following statements are true or false Non -metals do not react with water though they may be very reactive in air.
Answer» ANSWER :1

Discussion

429.	State whether the following statements are true or false Sulphur reacts with oxygen to form sulphur dioxide.
Answer» ANSWER :1

Discussion

430.	State whether the following statements are true or false Metals produce ringing sound when struck hard.
Answer» ANSWER :1

Discussion

431.	State whether the following statements are true or false : Carbon monoxide reduces the oxygen-carrying capacity of the blood.
Answer» ANSWER :1

Discussion

432.	State whether the following statements are true or false: Coke is a tough, porous and black substance.
Answer» ANSWER :1

Discussion

433.	State whether the following statements are true or false : If there is excess of carbon dioxide in the air, it acts as a pollutant.
Answer» ANSWER :1

Discussion

434.	State whether the following statements are true or false: Coal was used for street lightning for the frst time in london.
Answer» ANSWER :1

Discussion

435.	State whether the following statement is true or false : Kerosene has lower ignition temperature than wood.
Answer» ANSWER :A

Discussion

436.	State whether the following statement is true or false : LPG and candle burn with a flame.
Answer» ANSWER :A

Discussion

437.	State whether the following statement is true or false : Fuel efficiency is expressed in terms of its calorific value.
Answer» ANSWER :A

Discussion

438.	State whether the following statement is true or false : Fire extinguishers cut off the supply of air and lower the temperature.
Answer» ANSWER :A

Discussion

439.	State the uses of the followign non-metals. (a) Oxygen (b) Chlorine (c )Sulphur
Answer» Solution :(i) RESPIRATION (ii) Bleaching ACTION (iii) FUNGICIDES

Discussion

440.	State the postulates of Bohr's theory.
Answer» SOLUTION :(i) Definite ENERGY (II) TRANSITION of ELECTRONS.

Discussion

441.	State the physical properties of diamond.
Answer» Solution :(i) COLOUR (ii) Density (iii) REFRACTIVE index (IV) Conduction of heat and electricity .

Discussion

442.	State the electronic configuration of sodium based on thediagram given.
Answer» ANSWER :2, 8 , 1

Discussion

443.	State one property of germanium which shows its acidic nature.
Answer» SOLUTION :REACTIVITY of GE with `O_(2)`

Discussion

444.	Spontaneous forest fires are sometimes due to the heat of the __________ or _________.
Answer»

Discussion

445.	Some of the hydrated crystals are efflorescent . How do you account for this ?
Answer» Solution :The vapour pressure of these HYDRATED crystals is GREATER than that of the wter vapour present in the atmosphere at ROOM TEMPERATURE.

Discussion

446.	How are the elements with variable valency named ? Explain with an example.
Answer» ANSWER :T

Discussion

447.	Solvent is formed by dissolving solute in a solution.
Answer» ANSWER :F

Discussion

448.	Solubility of coppe sulphate in water is 20.7 grams at 20^(@)C . What do you mean by this statement ?
Answer» SOLUTION :20.7 grams of `CuSO_(4)` is PRESENT 100 grams of water.

Discussion

449.	Solubility curves can be used for comparing the solubility of different substances at a given temperature .
Answer» ANSWER :1

Discussion

450.	Solids have negligible.. .. but strong ________
Answer» SOLUTION :inter-particle SPACE, inter-particle FORCE of ATTRACTION

Discussion

Explore topic-wise InterviewSolutions in .

Temporary and reverisble changes are called ……….. Changes

Tornado can be called a periodic change.

Talk to your parents or grandparents about the types of buckets that were used in the past. What is the material of the buckets or mugs you are using today? What are the advantages of using a plastic container?

Symbolic representation of an element.

Symbolic expression for a molecule is called ………………. .

Symbolic representation of a chemical reaction.

Suppose you have two boxes similar in appearance, one made of wood and the othermade of metal. Can you tell which boa is made of metal by striking both the boxes?

Sulphur, on heating follows Which of the following sequence?

Sulphur on reaction with HNO_3 gives "__________"

Sugar on reaction with _______ gives sugar charcoal.

Sugar, on being treated withH_2SO_4, forms a black residue. If we observe the weights of sugar and the residue, we find a difference m weights. Why?

Sugar is a ................. . (mixture/compound)

Sugar charcoal is good reducing agents.

Substances with different densities can be separated by

Substance with low ________ can catch fire easily.

Substance used in the preparation of carbon dioxide along with dil. HCl

Substance formed by burning of wood in limited oxygen.

Sublimation is a chemical change

Sublimation is a change in a substance from .............. state to...... State.

Stibnum is the Latin name of__________ .

"Steam at 100^(@)C causes more burnswhen exposed ot skin than water at 100^(@)C ". Justify.

State whther the following statement is true or false : Fabrics are made from fibres obtained from natural or artificial sources.

State whether the following statements are true or false There are no more than 94 naturally occurring element.

State whether the following statements are true or false Oxides of non-metals are acidic in nature.

State whether the following statements are true or false Non -metals do not react with water though they may be very reactive in air.

State whether the following statements are true or false Sulphur reacts with oxygen to form sulphur dioxide.

State whether the following statements are true or false Metals produce ringing sound when struck hard.

State whether the following statements are true or false : Carbon monoxide reduces the oxygen-carrying capacity of the blood.

State whether the following statements are true or false: Coke is a tough, porous and black substance.

State whether the following statements are true or false : If there is excess of carbon dioxide in the air, it acts as a pollutant.

State whether the following statements are true or false: Coal was used for street lightning for the frst time in london.

State whether the following statement is true or false : Kerosene has lower ignition temperature than wood.

State whether the following statement is true or false : LPG and candle burn with a flame.

State whether the following statement is true or false : Fuel efficiency is expressed in terms of its calorific value.

State whether the following statement is true or false : Fire extinguishers cut off the supply of air and lower the temperature.

State the uses of the followign non-metals. (a) Oxygen (b) Chlorine (c )Sulphur

State the postulates of Bohr's theory.

State the physical properties of diamond.

State the electronic configuration of sodium based on thediagram given.

State one property of germanium which shows its acidic nature.

Spontaneous forest fires are sometimes due to the heat of the __________ or _________.

Some of the hydrated crystals are efflorescent . How do you account for this ?

How are the elements with variable valency named ? Explain with an example.

Solvent is formed by dissolving solute in a solution.

Solubility of coppe sulphate in water is 20.7 grams at 20^(@)C . What do you mean by this statement ?

Solubility curves can be used for comparing the solubility of different substances at a given temperature .

Solids have negligible.. .. but strong ________

Spontaneous forest fires are sometimes due to the heat of the __ or _.