The atomic number of an element is 8. How many electrons will it gain to form a compound with sodium?
One
Two
Three
Four
B.
Two
Which one of the following will NOT produce carbon dioxide on reacting with an aqueous solution of hydrochloric acid?
Limestone
Quick Lime
Chalk
Marble
Tooth enamel is made up of which one of the following calcium compounds?
Calcium carbonate
Calcium sulphate
Calcium hydroxide
Calcium phosphate
Which one of the following is an example of Salt Crystal growth?
Chemical weathering
Physical weathering
Biological weathering
Biological weathering
A sample of oxygen contains two isotopes of oxygen with masses 16 u and 18 u respectively. The proportion of these isotopes in the sample is 3 : 1. What will be the average atomic mass of oxygen in this sample?
17.5 u
17 u
16 u
16.5 u
On exposure to moist air, copper gains a green coat on its surface due to formation of which one of the following compounds?
Copper carbonate
Copper oxide
Copper sulphate
Copper nitrate
Who among the following has explained the phenomenon of photoelectric effect?
Max Planck
Albert Einstein
Neils Bohr
Ernest Rutherford