291. 75 gm of sugar solution has 30% sugar in it. Then the quantity of sugar that should be added to the solution to make the quantity of the sugar 70% in the solution, is

1. 1. 125 gm

   
   
   

   2. 100 gm

   
   
   

   3. 120 gm

   
   
   

   4. 130 gm

   
   
   

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1. View Hint View Answer Discuss in Forum

   Sugar in original solution =	75 × 30	= 22.5 gm
   	100

   
   Let m gm of sugar be mixed.
   

   ∴	22.5 + m	× 100 = 70
   	75 + m

   
   ⇒ 2250 + 100m = 75 × 70 + 70m
   ⇒ 2250 + 100m = 5250 + 70m
   

   Correct Option: B

   Sugar in original solution =	75 × 30	= 22.5 gm
   	100

   
   Let m gm of sugar be mixed.
   

   ∴	22.5 + m	× 100 = 70
   	75 + m

   
   ⇒ 2250 + 100m = 75 × 70 + 70m
   ⇒ 2250 + 100m = 5250 + 70m
   ⇒ 30m = 5250 – 2250 = 3000
   

   ⇒ m =	3000	= 100 gm
   	30

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292. A vessel has 60 litres of solution of acid and water having 80% acid. How much water be added to make it a solution in which acid forms 60% ?

1. 1. 48 litres

   
   
   

   2. 20 litres

   
   
   

   3. 36 litres

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   In 60 litres of solution,
   

   Water =	60 × 20	= 12 litres
   	100

   
   On adding m litres of water,
   

   	12 + m	× 100 = 40
   	60 + m

   
   

   Correct Option: B

   In 60 litres of solution,
   

   Water =	60 × 20	= 12 litres
   	100

   
   On adding m litres of water,
   

   	12 + m	× 100 = 40
   	60 + m

   
   ⇒ 60 + 5m = 120 + 2m
   ⇒ 3m = 60
   ⇒ m = 20 litres

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293. If 4 litres of water is evaporated on boiling from 12 litres of salt solution containing 7 percentage salt, the percentage of salt in the remaining solution is

1. 1. 10.5%

   
   
   

   2. 11.5%

   
   
   

   3. 12%

   
   
   

   4. 13%

   
   
   

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1. View Hint View Answer Discuss in Forum

   In 12 litres salt solution,
   

   Salt =	7 × 12	= 0 84 . units
   	100

   
   

   Water =	93 × 12	= 11.16. units
   	100

   
   

   Correct Option: A

   In 12 litres salt solution,
   

   Salt =	7 × 12	= 0 84 . units
   	100

   
   

   Water =	93 × 12	= 11.16. units
   	100

   
   After evaporation,
   

   Percentage of salt =	0.84	× 100 = 10.5%
   	8

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294. 1 litre of water is added to 5 litres of alcohol-water solution containing 40% alcohol strength. The strength of alcohol in the new solution will be

1. 1. 30%

   
   
   

   2. 33%

   
   
   

   3. 33	2	%
      	3

   
   
   

   4. 33	1	%
      	3

   
   
   

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1. View Hint View Answer Discuss in Forum

   According to question,
   

   Alcohol in original solution =	40	× 5 = 2 litres
   	100

   
   Water in original solution = 3 litres
   On adding 1 litre water, water becomes 4 litres.
   Now, 6 litres of solution contains 2 litres of alcohol.
   

   ∴ 100 litres of solution contains =	2	× 100
   	6

   
   

   Correct Option: D

   According to question,
   

   Alcohol in original solution =	40	× 5 = 2 litres
   	100

   
   Water in original solution = 3 litres
   On adding 1 litre water, water becomes 4 litres.
   Now, 6 litres of solution contains 2 litres of alcohol.
   

   ∴ 100 litres of solution contains =	2	× 100
   	6

   
   

   100 litres of solution contains =	100	= 33	1	% alcohol.
   	3		3

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295. A sample of 50 litres of glycerine is found to be adulterated to the extent of 20%. How much pure glycerine should be added to it so as to bring down the percentage of impurity to 5% ?

1. 1. 155 litres

   
   
   

   2. 150 litres

   
   
   

   3. 150.4 litres

   
   
   

   4. 149 litres

   
   
   

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1. View Hint View Answer Discuss in Forum

   Glycerine in mixture = 40 litres
   Water = 10 litres
   Let m litres of pure glycerine is mixed with the mixture.
   

   ∴	40 + m	=	95	=	19
   	50 + m		100		20

   
   

   Correct Option: B

   Glycerine in mixture = 40 litres
   Water = 10 litres
   Let m litres of pure glycerine is mixed with the mixture.
   

   ∴	40 + m	=	95	=	19
   	50 + m		100		20

   
   ⇒ 800 + 20m = 950 + 19m
   ⇒ m = 950 – 800 = 150 litres.

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