Chemistry Questions

The molar mass of H2O can be calculated as the following.

M(H2O)= [2 x M(H)] + [M(O)].

And we know that M(H) = 1g/mol, M(O) = 16g/mol.

So, M(H2O)= 2x1 + 16 = 18g/mol,

That means 1 mole of H2O contains 18g.

Hence, one mole of H2O corresponds to 18 grams.

The monomer of polythene is ethylene.

We will rewrite the formula as an equation.

2K + 2Cr + 7O = 0

The zero comes from there being no overall charge on the compound.

Each oxidation number is represented by the element's symbol.

Since this compound is not a peroxide or superoxide, the oxidation value for O is -2

K being in group 1 has a +1 charge and therefore has an oxidation number of K is +1

Now, by putting known values in we have:

2(+1) + 2(Cr) + 7(-2) = 0

2 + 2Cr -14 = 0

2Cr = +12

Cr = +6.

Mixtures are combination of two or more substances physically which can be separated in to the original.

Matter can be breakdown into two categories. 

1) Pure substances 

2) Mixtures

Here in the given options, options A, B, C are pure substances as they are indicated as S & L in brackets. Option D) is an aqueous solution, that can be dissolved in water.