1
JEE Main 2018 (Offline)
+4
-1
The density of a material in the shape of a cube is determined by measuring three sides of the cube and its mass. If the relative errors in measuring the mass and length are respectively 1.5% and 1%, the maximum error in determining the density is:
A
6%
B
2.5%
C
3.5%
D
4.5%
2
JEE Main 2018 (Online) 15th April Evening Slot
+4
-1
The characteristic distance at which quantum gravitational effects are significant, the Planck length, can be determined from a suitable combination of the fundamental physical constants G, h and c.

Which of the following correctly gives the Planck length ?
A
G $$\hbar$$2 c3
B
G2 $$\hbar$$ c
C
$${G^{{\raise0.5ex\hbox{\scriptstyle 1} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{\scriptstyle 2}}}}{\hbar ^2}c$$
D
$${\left( {{{G\hbar } \over {{c^3}}}} \right)^{{\raise0.5ex\hbox{\scriptstyle 1} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{\scriptstyle 2}}}}$$
3
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
The relative error in the determination of the surface area of sphere is $$\alpha$$. Then the relative error in the determination of its volume is :
A
$${3 \over 2}\alpha$$
B
$${2 \over 3}\alpha$$
C
$${5 \over 2}\alpha$$
D
$$\alpha$$
4
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
In a screw gauge, $$5$$ complete rotations of the screw cause it to move a linear distance of $$0.25$$ $$cm.$$ There are $$100$$ circular scale divisions. The thickness of a wire measured by this screw gauge gives a reading of $$4$$ main scale divisions and $$30$$ circular scale divisions. Assuming negligible zero error, the thickness of the wire is :
A
$$0.4300$$ $$cm$$
B
$$0.2150$$ $$cm$$
C
$$0.3150$$ $$cm$$
D
$$0.0430$$ $$cm$$
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