Answer:
methyl orange, methyl red,phenoptalin, merhy red
Explanation:
all this following are indicators use to check the end point of a reaction
Answer:
The pressure is the measure of force acting on a unit area. Density is the measure of how closely any given entity is packed, or it is the ratio of the mass of the entity to its volume. The relation between pressure and density is direct. Change in pressure will be reflected in a change in density
Answer:
option E
Explanation:
given,
I is moment of inertia about an axis tangent to its surface.
moment of inertia about the center of mass
.....(1)
now, moment of inertia about tangent

...........(2)
dividing equation (1)/(2)



the correct answer is option E
As per the question the wavelength of spectral line of the neutral hydrogen atom is 21 cm.
Spectral line of hydrogen atom will be observed when an electron will jump from higher excited to the ground state. If E is the energy of the ground state and E' is the energy of the higher excited state,the energy emitted when electron will jump from higher excited to ground state is E'-E.
As per Planck's quantum theory -

Where f is the frequency of emitted radiation and h is the Planck's constant.Actually this energy emitted is also electromagnetic in nature. We know that all the electromagnetic radiation will move with the same velocity which is equal to the velocity of light.
The velocity of light c= 3×10^8 m/s.Hence the velocity of wave corresponding to this spectral line is 3×10^8 m/s.
We know that velocity of a wave is the product of frequency and wavelength of that corresponding wave. Mathematically we can write it as-

[
is the wavelength of the wave ]
It is given that wavelength =21 cm=0.21 m
The frequency is calculated as -




Hence the antenna will be tuned to a frequency of 14.2857×10^8 Hz
Here Hertz[ Hz] is the unit of frequency.
Answer:
1.89mol
Explanation:
The entropy change during free expansion is express as

Where S is the entropy of the system,
n is the amount of mole
R is the gas constant = 8.314 and
V is the volume occupied at the initial and final stage
since the process is n adiabatic free expansion, the entropy of the system is constant. Hence we can re-write the equation as

where the
and 
and
Now if we substitute in values we arrive at
