1 ) Alkali metals form . . . . . . . . . . . . . ,
A ) covalent compounds , B ) ionic compounds ,
C ) both , D ) none of these ,
Correct Answer : - B ) ionic compounds ,
2 ) Washing soda has formula : - Na2CO3 10.H2O .
3 ) Net charge on ferrous ion is ( + 2 ) and ferric ion is ( + 3 ) .
4 ) The total number of protons in 10 g of calcium carbonate is ? ( NA = 6.023 x 10 ^ 23 ) .
A ) 15 x 10 ^ 20 , B ) 30 x 10 ^ 23 ,
C ) 34 x 10 ^ 27 , D ) None of these ,
Correct Answer : - B ) 30 x 10 ^ 23 ,
Solution : -
No. of protons in CaCO3 = 20 + 6 + 24 = 50 .
Total no. of protons = moles x ( no. of protons ) x NA .
Total no. of protons = ( 10 / 100 ) x 50 x ( 6.023 x 10 ^ 23 ) ,
Total no. of protons = 30 x 10 ^ 23 , Answer .
5 ) In Potassium super oxide ( KO2 ) , the oxidation state of O is : - - 1 / 2 .
A ) 1 , B ) - 1 / 2 ,
C ) 1 / 2 , D ) None of these ,
Correct Answer : - B ) - 1 / 2 ,
6 ) One mole of gas refers to the no. of molecules in 22.4 litres of a gas at STP .
7 ) Among the following pairs , the one which illustrate the law of multiple proportions is : -
A ) HCl , NH3 . B ) H2S , SO2 .
C ) CuO , Cu2O . D ) CS2 , FeSO4 .
Correct Answer : - C ) CuO , Cu2O .
Explanation : -
In option A ) charges on H is +1 , -3 . So incorrect .
In option B ) charges on S is -2 , +4 . So incorrect .
In option C ) charges on Cu is +2 , +2 . So correct .
In option D ) charges on S is -4 , +2 . So incorrect .
8 ) The element necessary for normal “ leaf ” development is calcium .
9 ) Lime ( CaO ) is often used as dehydrating agent .
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