The radius and height of a cylindrical cistern are $70 \,cm$ and $1.5 \,m$ respectively. How many litres of water can it hold?

$A$ room without a ceiling is $12 \, m$ long,$4 \, m$ wide,and $3 \, m$ high. Find the length of the longest rod that can be placed in that room. (in $m$)

Write True or False and justify your answer in each of the following: If the radius of a right circular cone is halved and height is doubled,the volume will remain unchanged.

Find the curved surface area and the total surface area of a hemisphere with a radius of $2.1 \, m$.

If the total surface area of a cone is $3696 \, cm^{2}$ and the curved surface area of a cone is $2310 \, cm^{2}$,find the ratio of the radius to the slant height.

$A$ cylindrical tube open at both ends is made of an iron sheet which is $2 \, cm$ thick. If the outer diameter is $16 \, cm$ and its length is $100 \, cm$, find how many cubic centimeters of iron have been used in making the tube? (in $cm^3$)