Quants

1. Learn, Implement & Practice
Science and Tech-3
Practice Questions
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2. Q1.
What is the name of that system which uses radioactivity to decide the
period of materials of pre his tone period ?
(a) Radium dating
(b) Uranium dating
(c) Carbon dating
(d) Deuterium dating
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3. Answer is C.
Radiocarbon dating (also referred to as carbon dating or carbon-14
dating) is a method for determining the age of an object containing
organic material by using the properties of radiocarbon, a radioactive
isotope of carbon. The method was developed in the late 1940s at the
University of Chicago by Willard Libby.
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4. Q2.
Which of the following gases is present under pressure in soft drinks?
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Nitrous oxide
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5. Option C Solution: Carbon dioxide is present under pressure in soft
drinks.
Carbonation, addition of carbon dioxide gas to a beverage, imparting
sparkle and a tangy taste and preventing spoilage. The liquid is chilled
and cascaded down in an enclosure containing carbon dioxide (either
as dry ice or a liquid) under pressure. Increasing pressure and lowering
temperature maximize gas absorption.
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6. Q3.
The substance which does not expand on going from liquid state to
solid state is
(a) Water
(b) Castiron
(c) Aluminium
(d) Type metal
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7. Answer is D. Type Metals is the substance which does not expand on
going from liquid to solid state. Type metal is nothing but an alloy of
lead, tin, and antimony, used for casting type.
In printing, type metal (sometimes called hot metal) refers to the metal
alloys used in traditional type founding and hot metal typesetting. Lead
is the main constituent of these alloys. Antimony and tin are added to
make the character produced durable and tough while reducing the
difference between the coefficients of expansion of the matrix and the
alloy. Pure metal melts and solidifies in a simple manner at a specific
temperature. This is not the case with alloys.
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8. Q4.
Which of the following is used to iodine common salt ?
(a) Potassium magnate
(b) Iodine
(c) Potassium iodide
(d) Sodium iodide
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9. Answer is C. Edible salt can be iodised by spraying it with a potassium
iodate solution.
Potassium iodide and potassium iodate are commonly added to table
salt to prevent iodine deficiency and associated thyroid disease.
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10. Q5.
The major harmful gas emitted by automobile vehicle which causes air
pollution is
(a) Carbon Monoxide
(b) Methane
(c) Carbon dioxide
(d) Ozone gas
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11. Carbon monoxide (CO) is a poisonous gas that is emitted from the
engine of an automobile. The smoke released from the automobile is
due to the combustion of fuels like petrol and diesel
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12. Q.6 What is "milk of magnesia” chemically ?
(a) Magnesium carbonate
(b) Sodium bicarbonate
(c) Calcium hydroxide
(d) Magnesium hydroxide
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13. Answer: Option D Solution: Magnesium hydroxide is the inorganic
compound with the chemical formula Mg(OH)₂. It occurs in nature as
the mineral brucite. It is a white solid with low solubility in water.
Magnesium hydroxide is a common component of antacids, such as
milk of magnesia, as well as laxatives
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14. Q7.
The natural source of hydrocarbon is
(a) Crude oil
(b) Biomass
(c) Coal
(d) Carbohydrates
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15. Answer is A.
The natural sources of hydrocarbons include coal, petroleum, and
natural gas.

16. Q8.
Nucleus of an atom consists of
(a) Proton
(b) Neutron
(c) Proton and Neutron
(d) Electron Proton and Neutron

17. • Correct option is C)
• The nucleus of the atom consists of protons and neutrons. Electrons
are present outside the nucleus.
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18. Q9.
The presence of ozone in the stratosphere is responsible for
(a) increasing the average global temperature in recent years
(b) higher rate of photosynthesis
(c) checking the penetration of ultraviolet rays to the earth
(d) supplying oxygen for people travelling in jets
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19. Answer is C,
Ozone in the stratosphere protects us from the Sun's harmful
ultraviolet rays. However, ozone in the troposphere, closer to Earth's
surface, is a pollutant and hazardous to our health.
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20. Q10.
The advantage of detergents over soaps is
(a) Detergents are soluble in water
(b) Detergents could not give much lather
(c) Detergents give lather even with hard Water
(d) Soaps give lather with only soft water
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21. • Correct option is C)
• An advantage of detergents over soaps is that detergents do not
precipitate in hard water, unlike soap, and clothes can be easily
washed with detergents in hard water. This is because detergents are
chemically synthesized (artificial hydrocarbon chains) in a way that
metal ions do not make compounds with the hydrocarbon chains, and
cleansing action can be carried on.
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22. Q11.
What is the element required for solar energy conversion ?
(a) Beryllium
(b) Tantalum
(c) Silicon
(d) Ultra pure carbon
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23. The most prevalent bulk material for solar cells is crystalline silicon
(abbreviated as a group as c-Si), also known as “solar grade silicon”.
Bulk silicon is separated into multiple categories according to
crystallinity and crystal size in the resulting ingot, ribbon, or wafer.
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24. Q12.
Cloud is a colloidal dispersion of
(a) Air in a dispersion medium of water
(b) Fog in a dispersion medium of water
(c) Mist in a dispersion medium of air
(d) Water drops in a dispersion medium of air
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25. • Correct option is D)
• The clouds consist of charged particles of water dispersed in air. Some
of them are +vely charged, others are -vely charged.
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26. Q13.
Which of the following is used in making smoke bombs?
(a) Sulphur
(b) Phosphorus
(c) Hydrogen
(d) Carbon
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27. • Hint: Although modern smoke grenades are designed not to directly emit sparks or any fire but they remain
a fire hazard and are capable of igniting dry vegetation or flammable substances if used unwisely. White
phosphorus burns with a brilliant yellow flame while producing ample amounts of white smoke which is
phosphorus pentoxide (P4O10) .
• Complete step by step answer:
A smoke bomb is a well-known firework designed to produce smoke when ignited. Smoke bombs are most
necessarily used in military units, airsoft games, paintball games, self-defence and pranks. The very first
smoke bomb was created by the inventor Robert Yale in 1848. Robert Yale developed 17th century Chinese-
style fireworks and later on modified the formula to produce more and more smoke for a longer period of
time. The formula that is used by Coloured smoke devices consists of an oxidizer, a fuel generally sugars,
potassium chlorate (KClO3) , a moderator, such as sodium bicarbonate (NaHCO3) to keep the reaction from
getting too hot, and a powdered organic dye. The burning of this mixture evaporates the dye and forces it
out of the device, where it condenses in the atmosphere to form a smoke which is finely dispersed particles.
A smoke ball is a hollow and cherry-sized sphere of brightly coloured clay filled with a smoke-generating
composition that produces a forceful jet of coloured smoke for good 10 to 15 seconds.
• Therefore, the correct answer is option (B).
• Note: The military uses smokes most probably WP to protect friendly forces, identify enemy targets and
tactical locations, support deception operations, and to obscure certain reconnaissance activities,
surveillance, and targets from enemy forces.
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28. Q14.
Metal are good conductors because
(a) they contain free electrons
(b) the molecules in them are very close to each other
(c) the molecules in them collide Very freely
(d) they contain reflecting surface
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29. The free electrons come from the electrically neutral metal atoms. The
unwanted electrons created by the metallic bonding are the "free"
electrons that make metals good conductors
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30. Q15.
Greenhouse effect is caused by
(a) nitrogen
(b) carbon dioxide
(c) carbon monoxide
(d) nitrogen dioxide
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31. Answer is B.
Solution: Earth's greenhouse gases trap heat in the atmosphere and
warm the planet. The main gases responsible for the greenhouse effect
include carbon dioxide, methane, nitrous oxide, and water vapour
(which all occur naturally), and fluorinated gases (which are synthetic)
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32. Q16.
The major constituent of air is
(a) nitrogen
(b) carbon dioxide
(c) oxygen
(d) hydrogen
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33. Answer is A.
The major constituent of air is nitrogen. Air consists of 78% nitrogen,
21% oxygen and 1% of other gases, dust, impurities, water vapour.
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34. Q17.
Which metal is extracted from seawater?
(a) Potassium
(b) Magnesium
(c) Aluminium
(d) Beryllium
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35. Answer: Option B Solution: The elements dissolved in sea water have
been commercially extracted in many quantity. They are sodium and
chlorine in the form of common salt, magnesium and some of its
compounds, and bromine.
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36. Q18.
Pasteurization is the process in which milk is heated to
(a) 60°C for 10 minutes .
(b) 63° C for 20 minutes
(c) 63°C for 30 minutes
(d) 72°C for 10 minutes
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37. Pasteurization (or pasteurisation) is a process of heating a food, which is
usually a liquid, to a specific temperature for a predefined length of time and
then immediately cooling it after it is removed from the heat. This process
slows spoilage due to microbial growth in the food. Unlike sterilization,
pasteurization is not intended to kill all micro-organisms in the food. Instead,
it aims to reduce the number of viable pathogens so they are unlikely to
cause disease (assuming the pasteurized product is stored as indicated and is
consumed before its expiration date). Commercial-scale sterilization of food
is not common because it adversely affects the taste and quality of the
product. Certain foods, such as dairy products, may be superheated to
ensure pathogenic microbes are destroyed. A less conventional but US FDA-
legal alternative (typically for home pasteurization) is to heat milk at (63
degree C) for 30 minutes.
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38. Q19.
The gas used in the artificial ripening of fruits is
(a) Acetylene
(b) Methane
(c) Ethane
(d) Butane
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39. Ethylene gas, acetylene gas liberated from calcium carbide, and
ethephon are some of the commercial ripening agents used
successfully in the trade and they have been widely studied for their
effectiveness on initiating and accelerating the ripening process and
their effect on fruit quality and health related issues.
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40. Q20.
The freezer in a refrigerator is fitted near the top
(a) to keep it away from hot compressor which is nearer to the bottom
(b) because of convenience
(c) it facilitates convection currents .
(d) to minimize power consumption
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41. The freezer in a refrigerator is fitted near the top so that it can cool the
whole interior by setting up convection currents. Most household freezers
maintain temperatures from (-23 to -18 degree C), although some freezer-
only units can achieve (-34 degree C), and lower. Refrigerators generally do
not achieve lower than (-23 degree C), since the same coolant loop serves
both compartments: Lowering the freezer compartment temperature
excessively causes difficulties in maintaining above-freezing temperature in
the refrigerator compartment. Domestic freezers can be included as a
separate compartment in a refrigerator, or can be a separate appliance.
Domestic freezers are generally upright units resembling refrigerators, or
chests (resembling upright units laid on their backs). Many upright modern
freezers come with an ice dispenser built into their door.
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