1
JEE Main 2019 (Online) 11th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The de Broglie wavelength ($$\lambda $$) associated with a photoelectron varies with the frequency (v) of the incident radiation as, [v0 is threshold frequency] :
A
$$\lambda \,\infty \,{1 \over {{{\left( {v - {v_0}} \right)}^{{3 \over 2}}}}}$$
B
$$\lambda \,\infty \,{1 \over {{{\left( {v - {v_0}} \right)}^{{1 \over 4}}}}}$$
C
$$\lambda \,\infty \,{1 \over {\left( {v - {v_0}} \right)}}$$
D
$$\lambda \,\infty \,{1 \over {{{\left( {v - {v_0}} \right)}^{{1 \over 2}}}}}$$
2
JEE Main 2019 (Online) 11th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
25 ml of the given HCl solution requires 30 mL of 0.1 M sodium carbonate solution. What is the volume of this HCl solution required to titrate 30 mL of 0.2 M aqueous NaOH solutions ?
A
50 mL
B
12.5 mL
C
25 mL
D
75 mL
3
JEE Main 2019 (Online) 11th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
$$\underline A \,\,\buildrel {4KOH,{O_2}} \over \longrightarrow \,\,\mathop {2\underline B }\limits_{\left( {Green} \right)} \,\, + \,\,2{H_2}O$$

$$3\underline B \,\,\buildrel {4HCl} \over \longrightarrow \,\,\mathop {2\underline C }\limits_{\left( {Purple} \right)} \,\, + \,\,Mn{O_2} + 2{H_2}O$$

$$2\underline C \,\,\buildrel {{H_2}O.KI} \over \longrightarrow \,\,\mathop {2\underline A }\limits_{\left( {Purple} \right)} \,\, + \,\,2KOH\,\, + \,\,\underline D $$

In the above sequence of reactions, $${\underline A }$$ and $${\underline D }$$, respectively, are :
A
Kl and KMnO4
B
Kl and K2MnO4
C
KlO3 and MnO2
D
MnO2 and KlO3
4
JEE Main 2019 (Online) 11th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The standard reaction Gibbs energy for a chemical reaction at an absolute temperature T is given by $$\Delta $$rGo = A – BT

Where A and B are non-zero constants. Which of the following is TRUE about this reaction?
A
Exothermic if B < 0
B
Endothermic if A > 0
C
Exothermic if A > 0 and B < 0
D
Endothermic if A < 0 and B > 0
JEE Main Papers
2023
2021
EXAM MAP
Medical
NEETAIIMS
Graduate Aptitude Test in Engineering
GATE CSEGATE ECEGATE EEGATE MEGATE CEGATE PIGATE IN
Civil Services
UPSC Civil Service
Defence
NDA
Staff Selection Commission
SSC CGL Tier I
CBSE
Class 12