In which of the following is the oxidation number of nitrogen zero?
A. SO2 and NH3
B. NaNO3
C. HNO2
D. NOI3
E. N2
E
3.
The separation of a mixture of calcium trioxocarbonate (lV) and sodium trioxocarbonate (IV) is most easily carried out by using the differences in their
A. physical states
B. melting points
C. values
D. solubility
E. boiling points
D
4.
When air is passed through a heated tube containing finely divided copper, the component that is absorbed in the process is
A. carbon (IV) oxide
B. nitrogen
C. oxygen
D. water vapour
E. noble gases
C
5.
What is the amount (in mole) of sodium trioxocarbonate (IV) in 5.3 g of the compound? (Na2CO3 = 106)
A. 0.05
B. 0.10
C. 0.20
D. 0.50
E. 2.00
A
6.
Which of the processes represented by the following equations has the greatest positive entropy change?
A. C6H3(l) → C6H 6(g)
B. H2O (s) → H2O(l)
C. CuO(s) + H2(g) → Cu(s) + H2
D. Na2CO3(s) + nH2O(l) →Na 2CO3nH2O(s)
E. S(s) → S(l)
A
7.
Which of the following elements can from more than one acidic oxide?