Did Dobereiner's triads also exist in the columns of Newland's Octaves? Compare and find out.

From a solid cylinder whose height 8 cm and radius 6 cm, a conical cavity of height 8 cm and a base radius 6 cm is hollowed out. Find the volume of the remaining solid. Also find the total surface area of the remaining solid.

On comparing the rations a_1/a_2,b_1/b_2 and c_1/c_2 ,find out whether the lins representing the following pairs of linear equations intersect at a point,are parallel or coincide:(i) 5x-4y+8=0 ;7x+6y-9=0

On comparing the rations a_1/a_2,b_1/b_2 and c_1/c_2 ,find out whether the lins representing the following pairs of linear equations intersect at a point,are parallel or coincide:(ii)9x+3y+12=0 ; 18x+6y+24=0

On comparing the ratios a_1/a_2,b_1/b_2 and c_1/c_2 ,find out whether the lines representing the following pairs of linear equations intersect at a point,are parallel or coincide:(iii)6x-3y+10=0 ;2x-y+9=0

Find out from table ,the medium having highest optical density. Also find the medium with lowest optical density.

Liquids generally have lower density as compared to solids. But you must have oberved that ice floats on water. Find out why.

What is the radius of the path of an electron moving at a speed of 10^7m//s in a magnetic field of 2xx10^(-4) T perpendicular to it? Also find out its frequency and energy.

Form the pair of linear equations in the following problems,and find their solutions(if they exist) by the elimination method:(iii) The sum of the digits of a two-digit number is 9.Also nine times this number is twice the number obtained by reversing the order of the digits.Find the number.

How many cubic meters of soil shall be taken out while digging a well of depth of 22.5m and diameter 7m.?Also find the total cost of cementing the curved surface inside the well at the cost of Rs.20 per square metre.