model 10 percentage with allegations & mixture Section-Wise Topic Notes With Detailed Explanation And Example Questions

Question : 1

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

a) 33$1/3$%

b) 30%

c) 33%

d) 33$2/3$%

Question : 2

In what ratio must a mixture of 30% alcohol strength be mixed with that of 50% alcohol strength so as to get a mixture of 45% alcohol strength ?

a) 3 : 1

b) 1 : 2

c) 1 : 3

d) 2 : 1

Question : 3

An ore contains 25% of an alloy that has 90% iron. Other than this, in the remaining 75% of the ore, there is no iron. To obtain 60 kg of pure iron, the quantity of the ore needed (in kgs) is approximately :

a) 300

b) 250.57

c) 266.67

d) 275.23

Question : 4

8 litres of water is added to 32 litres of a solution containing 20% of alcohol in water. What is the approximate concentration of alcohol in the solution now ?

a) 24%

b) 16%

c) 8%

d) 12%

Question : 5

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

a) 13%

b) 10.5%

c) 11.5%

d) 12%

Question : 6

How much pure alcohol has to be added to 400 ml of a solution containing 15% of alcohol to change the concentration of alcohol in the mixture to 32% ?

a) 68 ml

b) 60 ml

c) 100 ml

d) 128 ml