1 micro gram of Strontium-90 has an activity of
0.0000053 terabecquerels (TBq),
Explanation:
Given information denotes that .,one gram of Strontium-90 has an activity of 5.3 terabecquerels (TBq)
the activity of 1 micro gram is
1 gram = 1,000,000 micro gram has activities of 5.3 terabecquerels
therefore 1 micro gram has the activity of (5.3 ÷ 1,000,000 = 0.0000053 )
= 
Hence ., 1 micro gram of Strontium-90 has an activity of
0.0000053 terabecquerels (TBq),
The thickness of aluminium needed to stop the beam electrons, protons and alpha particles at the given dfferent kinetic energies is 1.5 x 10⁻¹⁴ m.
<h3>
Thickness of the aluminum</h3>
The thickness of the aluminum can be determined using from distance of closest approach of the particle.

where;
- Z is the atomic number of aluminium = 13
- e is charge
- r is distance of closest approach = thickness of aluminium
- k is Coulomb's constant = 9 x 10⁹ Nm²/C²
<h3>For 2.5 MeV electrons</h3>

<h3>For 2.5 MeV protons</h3>
Since the magnitude of charge of electron and proton is the same, at equal kinetic energy, the thickness will be same. r = 1.5 x 10⁻¹⁴ m.
<h3>For 10 MeV alpha-particles</h3>
Charge of alpah particle = 2e

Thus, the thickness of aluminium needed to stop the beam electrons, protons and alpha particles at the given dfferent kinetic energies is 1.5 x 10⁻¹⁴ m.
Learn more about closest distance of approach here: brainly.com/question/6426420
Answer:
1. Conduction
2. Convection
3. Radiation
Explanation:
The 3 modes of heat transfer i an air conditioning system:
1. Conduction:
The transfer of heat by conduction takes place in solid and is when the conduction takes place as a result of direct contact in between the interacting material which transfer the heat energy from particle to particle thus conducting the heat through out the system.
2. Convection:
The other mode for the transfer of heat which takes place especially in fluids - gases and liquids is through the technique of convection in which the transfer of heat takes place by the circular motion of the atoms and molecules of the fluid which carries the heat energy and results in the distribution of the heated fluid in the entire system thus transferring all the heat energy in the entire system.
3. Radiation:
The third mode of heat transfer in the air conditioning system is through radiation. This method transfers the heat by making use of the electro-magnetic radiation in the infra red spectrum where the waves of the spectrum transfers the heat energy with the help of a medium or without any medium at all.
Thus making the radiation method of heat transfer as the only method out of the three methods which does not require the material medium for the transfer of heat energy.
Answer:
Racking is the term used for when buildings tilt as their structural components are forced out of plumb. This is most commonly caused by wind forces exerting horizontal pressure, but it can also be caused by seismic stress, thermal expansion or contraction, and so on.
Explanation:
Neither, I would choose a PC because normally with PlayStation and Xbox you have to go to the store to buy more games when on a PC there are some games for free