The number of protons in an atom identifies the Atomic Number
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Missing part in the text of the problem:
"<span>Water is exposed to infrared radiation of wavelength 3.0×10^−6 m"</span>
First we can calculate the amount of energy needed to raise the temperature of the water, which is given by

where
m=1.8 g is the mass of the water

is the specific heat capacity of the water

is the increase in temperature.
Substituting the data, we find

We know that each photon carries an energy of

where h is the Planck constant and f the frequency of the photon. Using the wavelength, we can find the photon frequency:

So, the energy of a single photon of this frequency is

and the number of photons needed is the total energy needed divided by the energy of a single photon:
Answer:
a = 603.59 m/s^2
Explanation:
from the data given . the rate of change in magnetic field is as follow

from the faraday's law of induction , the expression for the induced emf in region of radius r as follow




electric field at point P_1 as follow



from newton 2nd law of motion, the acceleration of proton is
F = ma
qE = ma


a = 603.59 m/s^2
Answer:
Centripetal acceleration.
Explanation:
Centripetal acceleration is a property of a body moving in a uniform circular path and it is directed radially towards the center of the circle in which body is rotating.
The force which causes this acceleration is centripetal force which is also directed towards the center of the circle and pulls the body towards its center.
It is calculated through following formula

where v is velocity and r is the radius of the circle.
Answer:
Aluminium
Explanation:
When a body is immersed in a liquid partly or wholly it experiences an upward force which is called buoyant force.
The amount of buoyant force depends on the volume of body immersed, density of liquid and the value of acceleration due to gravity.
Here, the density of liquid is same in both the cases and g be the same. So, here the amount of buoyant force depends on the volume of body immersed.
As the density of lead is more than the density of aluminium, so the volume of aluminium is more than lead, as volume is equal to mass divided by density. So, the buoyant force acting on the aluminium is more than lead.