Structure of the Atom — Science STD 9 — Question

Name a technique used to separate.Petrol and water:

When liquid takes up heat from the surrounding, the surrounding ____________?

The rusting of an iron object is called:

1. Corrosion and it is a physical as well as a chemical change.
2. Dissolution and it is a physical change.
3. Corrosion and it is a chemical change.
4. Dissolution and it is a chemical change.

1.008 grams of hydrogen combines with 35.453 g of chlorine to form 36.463 g of a pure compound (hydrogen chloride). Dalton's explanation for this experimental fact might be: 

Spacing between particles of gas can be decreased. Hence, __________?

A few substances are arranged in the increasing order ‘forces of attraction’ between their particles. Which one of the following represents a correct arrangement?

A definite volume but not a definite shape, is a property of:

In a sample of ethyl ethanoate (CH₃COOC₂H₅) the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it?

The correct increasing order of the boiling points of liquid oxygen, liquid argon and liquid nitrogen present in liquid air is:

Neon and chlorine have atomic numbers 10 and 17 respectively. Their valencies will be ______ and ______ respectively: