Question

total harnessis the sum of hardness due to
bicarbonates of Ca and Mg only
chlorides and sulphates of Ca and Mg only
both A and B
neither A nor B​

Answer 1

th power of 2, written in mathematics as √2 or 21⁄2, is the positive algebraic number that, when multiplied by itself, equals the number 2. Technically, it is called the principal square root of 2, to distinguish it from the negative number with the same property.

Geometrically is the length of a diagonal across a square with sides of one unit of length; this follows the Pythagorean theorem. It was probably the first number known to be irrational.[citation needed]

As a good rational approximation for the square root of two, with a reasonably small denominator, the frac is sometimes used.

the OEIS consists of the digits in the decimal expansion of the square root of 2, here truncated to 65 decimal places: