A 500 gm packet of tea is sold for Rs 80 and a tooth brush costing Rs 11 is given free with it. The shopkeeper thus makes a profit of 15% on it. What did the shopkeeper pay for it?

The place with which a 7-digit number starts in Indo-Arabic System is

For such questions we should know the places of digits in Indo-Arabian system. The key part is counting the zeros.

0.6395 × 1000 =

When multiplying a decimal number by power of 10, we shift the decimal by point by the value of power of the number.

The place value of 5 in the number 215783 in Indo-Arabic System is

For such questions, we have to be careful to count from behind.

The remainder of 2¹⁰⁰ when divided by 7 is

For such questions, we should know the rules of indices.

If n = 10800 then find the total number of divisors of n and the number of even divisors

For such questions, we should know how to find prime factors.

For the combustion of n - octane
C8H18 + O2 → CO2 + H2O at 25°C (ignoring resonance in CO2)

The lengths of parallel sides of trapezium are in the ratio 7 : 5 and the distance between them is 14cm The area of trapezium is 252 cm².Find the length of its parallel sides.

For such questions, we should know the formula of area of trapezium.

A so lid piece of metal in the form of a Cuboid of dimes ions 24 cm x 18 cm x 4 cm is melted down and casted into a cube Find length of each edge of cube.

For such questions, we should know the formulas of volume of different shapes. We have to remember that when any metal piece is melted, it's volume doesn't change. The change is there only in the dimensions of the metal piece.

Human body is an example

It takes 2.56 × 10^–3 equivalents of KOH to neutralise 0.1254 g H₂XO₄. The number of neutrons in X is

Calculate the weight of iron which will be converted into its oxide by the action of 18g of steam on it.

AB, A₂ and B₂ are diatomic molecules. If the bond enthalpies of A₂, AB and B₂ are in the ratio 1:1:0.5 and the enthalpy of formation of AB from A₂ and B₂ – 100 kJ mol^–1, what is the bond enthalpy of A_2</sub

The H – H bond energy is 430 kJ mole^–1 & Cl – Cl bond energy is 240 kJ mole^–1. (H)_f for HClis – 90kJ. The H – Cl bond energy is about

Entropy change involved in conversion of one mole of liquid water at 373 K to vapour at the same temperature (latent heat of vaporisation of water = 2.257 kJ g^–1).

The outermost shell electronic configuration 3d⁵, 4s² represents