1. Zn + 2HCl → ZnCl₂ + H₂↑
The above reaction is an example of _______.
a. Combination reaction
b. Double displacement reaction
c. Displacement reaction
d. Decomposition reaction
Answer: c. Displacement reaction
2. A reddish brown coloured element ‘x’ on hearting in air, becomes a black
coloured compound ‘Y’. X and Y are _____ and_____.
a. Cu, CuO
b. Pb, PbO
Answer: a. Cu, CuO
3. A student tests the p H of pure water using a p H paper. It is shows green colour. If a p 11 paper is used after adding lemon juice to water, colour will he obverse?
Answer: b. Red
4. Chemical volcano is an example of ________. (APRIL, JUNE – 2014)
a. Combination reaction
b. Decomposition reaction
Answer: Decomposition reaction
5. When crystals of lead nitrate on heating strongly produces ________ gas and the colour of the gas is ________. (JUNE – 2012)
Answer: Nitrogen dioxide (NO₂), reddish brown
6. When aqueous solution of silver nitrate and sodium chloride are mixed, ________ precipitate is immediately formed
Answer: a. White
7. Aluminium can displace Zinc metal from aqueous solution of Zinc sulphate because________.
a. zinc is more reactive than aluminium
b. aluminium is more reactive than zinc
Answer: aluminium is more reactive than zinc
8. To protect tooth decay, we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is _______ i n nature.
9. Vinegar is present in acetic acid. Curd contains ________ acid.
a. Lactic acid
b. Tartaric acid
Answer: a. Lactic acid
10. pH= -log 10[H+]. The pH of a solution containing hydrogen ion concentration of 0.001M solution is ________.
Answer: a. 3
- Periodic classification of Elements
1. In the modern periodic table, periods and groups are given. Periods and groups indicate ________.
a. Rows and Columns
b. Columns and Rows
Answer: a. Rows and Columns
2. The third period contains elements. Out of these elements, how many elements are non-metals?
Answer: b. 5
3. An element which is an essential constituent of all organic compounds belongs to the ________ group. (JUNE – 2014)
a. 14th group
b. 15th group
Answer: a. 14th group
4. Ore is used for the extraction of metals profitably . Bauxite is used to extract aluminium, it can be termed as ________ (SEP – 2014)
Answer: a. ore
5. Gold does not occur in the combined form. It does not react with air water. It is in the ________ state. (JUNE, SEP – 2014)
Answer: a. native