1
WB JEE 2020
MCQ (Single Correct Answer)
+1
-0.25
Change Language
What will be the mass of one atom of 12C?
A
1 amu
B
1.9923 $$ \times $$ 10-23g
C
1.6603 $$ \times $$ 10-22g
D
6 amu
2
WB JEE 2020
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Bond order of He2, $$He_2^ + $$ and $$He_2^{2 + }$$ are respectively
A
1, $${1 \over 2}$$, 0
B
0, $${1 \over 2}$$, 1
C
$${1 \over 2}$$, 1, 0
D
1, 0, $${1 \over 2}$$
3
WB JEE 2020
MCQ (Single Correct Answer)
+1
-0.25
Change Language
To a solution of a colourless efflorescent sodium salt, when dilute acid is added, a colourless gas is evolved along with formation of a white precipitate. Acidified dichromate solution turns green, when the colourless gas is passed through it. The sodium salt is
A
Na2SO3
B
Na2S
C
Na2S2O3
D
Na2S4O6
4
WB JEE 2020
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The reaction for obtaining the metal (M) from its oxide (M2O3) ore is given by

$${M_2}{O_3}(s) + 2Al(l)\buildrel {Heat} \over \longrightarrow A{l_2}{O_3}(l) + 2M(s)$$, (s = solid, l = liquid) in that case, M is
A
copper
B
calcium
C
iron
D
zinc
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