A chemist has one solution which is 50% acid and another solution which is 25 % acid. How much each should be mixed to make 10 litres of a 40 % acid solution ? (Use Cramer's rule to solve the problem).

A chemist has two solutions of hydrochloric acid in stock. One is 50% solution and the other is 80% solution. How much of each should be used to obtain 100ml of a 68% solution.

6 - 8% solution of acetic acid in water is called _______.

Collodion is a 4% solution of which one of the following compounds in alcohol – ether mixture?

(Allocation problem) A cooperative society of farmers has 50 hectare of land to grow two crops X and Y. The profit from crops X and Y per hectare are estimated as rs. 10,500 and Rs. 9,000 respectively. To control weeds, a liquid herbicide has to be used for crops X and Y at rates of 20 litres and 10 litres pre hectare. Further, no more than 800 litres of herbicide should be used in order to protect fish and wild life using a pond which collects drainage from this land. How much land should be allocated to each crop so as to maximise the total profit of the society?

Sumi wants to invest atmost Rs. 20,000 in VIII sereis National Savings Bonds and Kisan vikash Oathras. According to rules, she has to invest atleast Rs. 5000 in saving bonds and atmost Rs. 8000 in Kisan Pathra. If the rate of inerest on savings bond is 10% p.a and the rate of Kisan vikash Pathara is 15% p.a, how much money should she invest in each to ear maximum yearly income ? also find the maximum yearly income.

A solution of 8% boric acid is to be diluted by adding a 2% boric acid solution to it. The resulting mixture is to be more than 4% but less than 6% boric acid. If we have 640 litres of the 8% solution, how many litres of the 2% solution will have to be added?