Chemistry

Question 1

When magnesium ribbon burns in air, it burns in which colour

Answer 1

White flame

Question 2

Saturated compounds like lpg , burns with which flame

Answer 2

Blue flame

Question 3

Unsaturated compounds burns with which flame

Answer 3

Yellow flame

Question 4

Magnesium ribbon burns with a dazzling, white flame and changes into a white powder. It is formed due to the reaction between

Answer 4

Magnesium and oxygen

Question 5

State true or false

when calcium oxide reacts with water it forms quicklime

Answer 5

False , it forms slaked lime

Question 6

State true or false
when calcium oxide reacts with water. It forms slaked lime and it is an exothermic reaction and requires heat as a driving energy.

Answer 6

False , it releases heat

Question 7

When the vegetable matter turns into compost which of the following reaction is or are involved?
1)Combination reaction
2)decomposition reaction
3)combination and exothermic reaction
4)decomposition and exothermic reaction

Answer 7

4

Question 8

Which of the following is water gas?
a) CO+H2
b)CO+N2
c)CO+H2O
d)CO+NH3

Answer 8

a

Question 9

Which of the following is solid
1)Fe2O3
2)SO2
3)SO3
4)CO2

Answer 9

1

Question 10

When FeSO4 . 7H2O ( ferrous sulphate ) loses water
Then its colour turns from green to _______

Answer 10

White

Question 11

FeSO4 (ferrous sulphate )with heat forms

Answer 11

Fe2O3(ferric oxide- reddish brown) +SO2+SO3
Here SO2 and SO3 are gases and ferric oxide solid

Question 12

White silver chloride turns grey in sunlight. This is due to the _______ of silver chloride in to silver and chlorine by light.

Answer 12

Decomposition

Question 13

Name the chemical used in black and white photography

Answer 13

Silver chloride and silver bromide

Question 14

Ba(OH)2+NH4Cl —> BaCl2 +NH4OH is a endothermic reaction or exothermic reaction

Answer 14

Endothermic reaction

Question 15

Why does the iron nail become brownish in colour and the blue colour of copper sulphate solution fades in a reaction between both?

Answer 15

Because of displacement reaction

Question 16

Bose-Einstein condensate is a

Answer 16

fifth state of matter

The BEC is formed by working a gas of extremely low density, about one- hundred tons and the density of normal air to super low temperatures.

Question 17

The rate of evaporation of liquid does not depend upon

Answer 17

its mass

Question 18

Define isobars

Answer 18

Atoms of different elements with different atomic numbers, but same mass number

Question 19

In graphite, each carbon atom is bonded to three other carbon atoms

Answer 19

in the same plane giving a hexagonal array

Question 20

Employing chromatography, one cannot separate

Answer 20

radioisotopes

Question 21

Define chromatography.

Answer 21

Chromatography is the technique for the separation of those solvents, that dissolve in the same solvent.
Radioisotopes cannot be dissolve in the same solvent to separate it.

Question 22

‘‘Atomic number of an element is a more fundamental property than its atomic mass.’’ Who among the following scientists has made the above statement?

Answer 22

Henry Moseley

Question 23

Very small insoluble particles in a liquid may be separated from it by using

Answer 23

decantation

Question 24

Fischer projection always depicts, the molecule in_______ form

Answer 24

eclipsed

Question 25

When hot water is placed into an empty water bottle, the bottle keeps its shape and does not soften. What type of plastic is the water bottle made from ?

Answer 25

Thermosetting

Question 26

Two reactants in a flask at room temperature are producing bubbles of a gas that turn limewater milky. The reactants could be

Answer 26

magnesium carbonate and hydrochloric acid

Question 27

Which of the following characteristics is common to hydrogen, nitrogen, oxygen and carbon dioxide ?

Answer 27

H2, N2, O2 andCO2 are all gases at room temperature.

Question 28

____ are saturated hydrocarbons

Answer 28

Alkanes

Question 29

Diamond v/s Graphite

Answer 29

Diamond is harder Both have same percentage of carbon Graphite is a better conductor Diamond has different carbon-carbon distance in all directions

Question 30

Bright light is found to emit from photographer’s flashgun. Thus brightness is due to the presence of which one of the following noble gases?

Answer 30

Xenon

Question 31

Which of the following substances cause temporary hardness in water?

Answer 31

magnesium and calcium hydrogen carbonates [Mg(HCO ) and 3 Ca(HCO3)]2 It can be removed by boiling and Clark’s method.

Question 32

Which one of the following elements is used as a timekeeper in atomic clocks ?

Answer 32

Caesium

Question 33

______ dissolve in water to form acidic solution.

Answer 33

Carbon dioxide

Question 34

Pearl is a hard object produced within the soft tissues of a mollusk. Which one of the following is the main constituent of pearl?

Answer 34

The soft tissue of mollusc animal accumulateCaCO3 which makes the pearl in them

Question 35

The paste of a white material in water is used to maintain a fractured bone fixed in place. The white material used is called

Answer 35

Plaster of Paris

Question 36

Which one of the following types of glasses is used for making optical instruments?

Answer 36

Hard glass

Question 37

What are the main constituents of biogas?

Answer 37

Methane and carbon dioxide

Question 38

One carbon credit is accepted as equivalent to

Answer 38

1000 kg of carbon dioxide Carbon credit is a generic term for any tradable certificate or permit representing the right to emit one tonne of carbon dioxide or the mass of another greenhouse gas with a carbon dioxide equivalent to one tonne of carbon dioxide.

Question 39

An emulsion consists of

Answer 39

two liquids

Question 40

Which one of the following radioactive substances enters/enter the human body through food chain and causes/ cause many physiological disorders ?

Answer 40

Strontium – 90

Question 41

Desalination of sea water is done by using reverse osmosis. The pressure applied to the solution is

Answer 41

larger than osmotic pressure

Question 42

Tincture of iodine is an antiseptic for fresh wounds. It is a dilute solution of elemental iodine, which contain

Answer 42

water alcohol potassium iodide 2-7% elemental iodine

Question 43

The pH value of a sample of multiple-distilled water is

Answer 43

very near to 7

Question 44

The handle of pressure cookers is made of plastic because it should be made non-conductor of heat. The plastic used there is the first man-made plastic, which is

Answer 44

bakelite

Question 45

Methyl isocyanate gas, which was involved in the disaster in Bhopal in December, 1984, was used in the Union Carbide Factory for production of

Answer 45

pesticides

Question 46

What is German silver?

Answer 46

German silver is an alloy of copper, zinc and nickel. It is called so as it appears like silver.

Question 47

Hydrogen has three known isotopes namely_____

Answer 47

protium, deuterium and tritium.

Question 48

The synthetic rubber has replaced natural rubber for domestic and industrial purposes. Which one of the following is the main reason behind that?

Answer 48

Raw materials for synthetic rubber are easily available

Question 49

Red phosphorus is used in the manufacture of safety matches. This is due to the fact that

Answer 49

at ordinary temperature, it is less reactive than other varieties of phosphorus