Classify the following into elements and compounds:

(i) H₂O (ii) He (iii) Cl₂ (iv) CO (v) Co

What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur?

Fill in the following blanks with suitable words:

(a) An element is made up of only one kind of ………….

(b) Brine is a ………… whereas alcohol is a ………….

(c) Brass is an alloy which is considered a ………….

(d) The three important metalloids are ………….

(e) The elements which are sonorous are called ………….

Classify the following as elements or compounds:

Iron, Iron sulphide, Sulphur, Chalk, Washing soda, Sodium, Carbon, Urea

What elements do the following compounds contain?

Sugar, Common salt