Questions

True, Water is a Pure substance and not a mixture.

We know that, A mixture is when two or more substances combine physically together. You can find that the mixture retains the properties of the original components.

In water, two hydrogen atoms combine with one oxygen atom chemically, forming a new substance that has properties different from hydrogen alone or oxygen alone.

Therefore, water is not a mixture; it is a compound and it is pure.

Sundari

Water is the important nutrient all organisms need. Humans has almost 60% of their body weight is water. Some organisms have 90% of their body weight is of water.

We know that polar substances are soluble in polar solvents and non polar substances are soluble in non-polar solvents only. Here the hydrocarbons are non-polar molecular substances and water is a polar solvent. So water can't dissolve hydrocabons.

Hence, as hydrocarbons are non-polar substances, they are insoluble in water as it is a highly polar solvent. 

8085 is a one address microprocessor. In 8085 interrupts  are classified by software and hardware interrupts.

DNA is a very long chain polymer made up of thousands of repeating units called nucleotides.

Nucleotide Unit is composed of a phosphate group, a pentose sugar, and a nitrogenous base.

The sides of the DNA ladder are made up of alternating deoxyribose sugar -- phosphate group units.