12 men complete the 2400 sq.m ploughing work in 10 days. How many men are required to complete 3600 sq. m ploughing work in 18 days?

2 men and 7 boys can do a piece of work in 14 days, 3 men and 8 boys can do the same in 11 days. In how many days, 3 times the work can be completed by 8 men and 6 boys?

The length, breadth and height of a hall are 8 m, 10 m, 4 m respectively and the hall has one door of area 3 m x 1.5 m. Find the cost of painting the walls at the rate of Rs. 200 per square metre.

If the capacity of a cylindrical tank is 1848 $ m^{3} $ and the diameter of its base is 14 m, then find the depth of the tank?

The length of a chain used as the boundary of a semicircular park is 72 m. What is the area
of the park?

Find the least number which when divided by 5, 6, 7 and 8 leaving a remainder 3, but when divided by 9 leaves no remainder.

Find the next number in the following series
4,6,9,$ 13\dfrac{1}{2} $

Consider the following statements :
Assertion (A): Scholars distinguished a culture midway between Palaeolithic and Neolithic called Mesolithic.
Reason (R) : The chief characteristics mesolithic were the stone implements used were extremely small and made up of Chalcedony and silicate instead of quartzite.
Select your answer according to the coding scheme below:

Match the following:
(a) Na and K - Obtained by electrolysis of fused salt
(b) Cu and Ag - Occur only in native state
(c) Au and Pt - Occur both native and combined state
(d) Na and Ca - Reducing agent in metallurgy
(e) Al and Mg - Occur only in combined state

Which of the following islare wrong?
I. $Mg_{2}C_{3}$ on hydrolysis gives acetylene
II. $Be_{2}C$ on hydrolysis gives methane
III. $Al_{4}C_{3}$ on hydrolysis gives allylene