Why must scientists be careful when studying nanotechnology?
1 answer:
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Explanation:
(a) First, we will calculate the number of moles as follows.
No. of moles =
Molar mass of helium is 4 g/mol and mass is given as 0.1 kg or 100 g (as 1 kg = 1000 g).
Putting the given values into the above formula as follows.
No. of moles =
=
= 25 mol
According to the ideal gas equation,
PV = nRT
or,
= 336.17 K
Hence, temperature change will be 336.17 K.
(b) The total amount of heat required for this process will be calculated as follows.
q =
=
= 174573.081 J/K
or, = 174.57 kJ/K (as 1 kJ = 1000 J)
Therefore, the amount of total heat required is 174.57 kJ/K.
1. C. Gravitational attraction exists between the two objects.
Explanation:
Gravitational attraction is always exerted between two objects which have mass, and its magnitude is given by:
where G is the gravitational constant, m1 and m2 the masses of the two objects, and r the separation between them. Since the two objects have for sure non-zero masses m1 and m2, even if they are 20 miles apart, the value of the gravitational attraction F is non-zero, so the correct answer is C.
2. D. Two atoms come together to form a molecule.
Explanation:
this outcome is actually caused by the electrostatic forces between the two atoms, not by gravitational force. In fact, gravitational force becomes relevant only when the masses of the two objects involved are large enough: this is the case for planets, stars, galaxies, and objects in the universe. However, two atoms have very small masses, so the gravitational force between them is really negligible. On this smaller scales, the electrostatic force is much stronger than the gravitational force, so the electrostatic force is the real responsible for the formation of bonds between atoms.