CIE Chemistry Paper-1: Specimen Questions 14 - 16 of 99
Question number: 14
What is always true for a pure substance?
It always boils at 100 °Celsius.
It is solid at room temperature
It has a sharp melting point.
It contains only one type of atom
A pure substance is homogeneous, i.e., has uniform composition throughout the whole sample. Pure substances display a sharp melting and boiling point which means that that the material goes from solid to liquid in a very short temperature range. An impure substance would have a melting point with a broader range.
Question number: 15
What is the relative molecular mass, Mr, of HNO3?
Relative molecular mass is the sum of all the relative atomic masses of the atoms in a molecule.
H = 1, N = 14, O = 16
Question number: 16
Describe in Detail
The diagram shows how to obtain pure water from seawater. Where do water molecules lose energy?
Here, Sea water contains .
- So, to obtain pure water ( ), there is a process called desalination is used to convert salt water into pure water.
- In this process, sea water is heated by any Bunsen flame as shown in upper figure to convert sea water into gas state.
- Then this gas is condensed to make it liquid which is called distillation process which gives pure water.