A Journey through States of Water MCQs for UPSC Prelims
110 practice questions covering A Journey through States of Water, organised into 0 topics.
110 questions include a written explanation.
Pick a topic below, or try the samples first.
Sample questions
Q1
easy
Tiny drops appear on the outside of a glass holding cold lemon water. Where do these drops come from?
AFrom the lemon water, which leaks out through the glass
BThe glass itself makes water when it is cold
CThey are small pieces of ice thrown out by the drink
DFrom water vapour present in the air around the glass
Show answer and explanation
Correct answer: D - From water vapour present in the air around the glass
Air always carries invisible water vapour, and the cold surface makes some of it turn into liquid drops. Glass has no holes for the drink to pass through, glass cannot create water, and the drops are liquid, not ice.
Q2
medium
Consider these statements. I. Melting and freezing are opposite changes. II. Evaporation changes a liquid into a gas. Which is correct?
AOnly I
BOnly II
CNeither I nor II
DBoth I and II
Show answer and explanation
Correct answer: D - Both I and II
Both statements are correct. Melting takes solid to liquid while freezing takes liquid back to solid, and evaporation is the quiet change from liquid to the gaseous state.
Q3
hard
A boy walks in from a cold veranda into a warm kitchen and his spectacles at once turn foggy. Where does the water on the lenses come from?
AFrom his eyes, which water in the warm room
BFrom vapour in the warm kitchen air, which condenses on the cold lenses
CFrom the cold outdoor air, which sticks to the lenses as he walks
DFrom water stored inside the glass of the lenses
Show answer and explanation
Correct answer: B - From vapour in the warm kitchen air, which condenses on the cold lenses
The lenses came in cold, and the kitchen air is warm and full of vapour, so vapour condenses the moment it touches them. Air itself does not stick as a wet film, glass stores no water, and tears would wet the inner side alone.
Q4
medium
Assertion (A): Wet clothes hung in the shade of a veranda still become dry. Reason (R): Water can evaporate only in direct sunlight.
ABoth A and R are true, and R is the correct explanation of A
BBoth A and R are true, but R is not the correct explanation of A
CA is true, but R is false
DA is false, but R is true
Show answer and explanation
Correct answer: C - A is true, but R is false
A is true, as anyone who dries clothes indoors knows. R is false, because evaporation takes place at every temperature; sunlight only makes it faster, so it is not a condition for evaporation.
Q5
easy
The forming of water drops on a cold surface is called
Amelting
Bboiling
Ccondensation
Devaporation
Show answer and explanation
Correct answer: C - condensation
Condensation is the change of water vapour into liquid water, which is exactly what happens on the cold surface. Evaporation is the reverse change, melting turns ice into water, and boiling needs strong heating.
Q6
medium
Ramesh has to dry a wet mop indoors on a damp day. Which step will help most?
AWrap it in a plastic sheet so that it stays clean
BLeave it bunched up in a still corner of the room
COpen it out fully and keep a fan blowing on it
DFold it and keep it inside a closed bucket
Show answer and explanation
Correct answer: C - Open it out fully and keep a fan blowing on it
Opening the mop increases the surface and the fan keeps carrying vapour away, so both helpful factors are used. A bucket, a still corner and a plastic wrap all trap humid air around the mop and slow evaporation to a crawl.
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