HARD
7th CBSE
IMPORTANT
Earn 100
Name the compounds formed by sodium. Also, write their chemical formulae.
Important Questions on Elements, Compounds and Chemical Equations
MEDIUM
7th CBSE
IMPORTANT
Explain the physical method by which salt can be separated from salty water.
HARD
7th CBSE
IMPORTANT
If the valency of calcium is , derive the valencies of the other elements or radicals present in the following compounds: Calcium chloride , Calcium hydroxide , Calcium phosphate .
MEDIUM
7th CBSE
IMPORTANT
When a dish containing ink is heated, we would observe evaporation is taking place. The dish heated continuously till no further change is seen and only dye is left behind. Was the original substance, i.e. ink an element, compound or mixture?
MEDIUM
7th CBSE
IMPORTANT
A balanced chemical equation for the reaction between sodium bicarbonate and hydrochloric acid is:
HARD
7th CBSE
IMPORTANT
Solve the crossword puzzle.
Across
4. Basic particles of matter
6. Atomicity of oxygen
7. Consists of only one type of atom
Down
1. He was the first one to use picture symbols to denote elements
2. Can be separated into constituents by simple physical methods
3. Molecules with positive or negative charges
5. The supporter of inflammable gas.
MEDIUM
7th CBSE
IMPORTANT
Using the definitions, decide whether the following diagram represents an element, a compound, or a mixture. Explain your choice.
MEDIUM
7th CBSE
IMPORTANT
Using the definitions, decide whether the following diagram represents an element, a compound, or a mixture. Explain your choice.
MEDIUM
7th CBSE
IMPORTANT
Using the definitions, decide whether the following diagram represents an element, a compound, or a mixture. Explain your choice.
