1
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The ratio of the shortest wavelength of two spectral series of hydrogen spectrum is found to be about 9. The spectral series are :
A
Paschen and Pfund
B
Balmer and Brackett
C
Lyman and Paschen
D
Brackett and Pfund
2
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
1 g of a non-volatile non-electrolyte solute is dissolved in 100 g of two different solvents A and B whose ebullioscopic constants are in the ratio of 1 : 5. The ratio of the elevation in their boiling points, $${{\Delta {T_b}(A)} \over {\Delta {T_b}(B)}}$$, is :
A
5 : 1
B
1 : 0.2
C
10 : 1
D
1 : 5
3
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The difference between $$\Delta $$H and $$\Delta $$U ($$\Delta $$H – $$\Delta $$U), when the combustion of one mole of heptane(l) is carried out at a temperature T, is equal to :
A
– 4 RT
B
3 RT
C
– 3 RT
D
4 RT
4
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The minimum amount of O2(g) consumed per gram of reactant is for the reaction :
(Given atomic mass : Fe = 56, O = 16, Mg = 24, P = 31, C = 12, H = 1)
A
4Fe(s) + 3O2(g) $$ \to $$ 2Fe2O3(s)
B
P4(s) + 5O2(g) $$ \to $$ P4O10(s)
C
C3H8(g) + 5O2(g) $$ \to $$ 3CO2(g) + 4H2O(l)
D
2Mg(s) + O2(g) $$ \to $$ 2MgO(s)
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