Answer: TWO.
At least two groups: treatment group and control group.
The treatment group is that is exposed to the different levels of the independent variable ( a medication for example), while the control group is not treated, so the researchers can compare the effect of the medication.
Answer: The coefficients for the given reaction species are 1, 6, 2, 3.
Explanation:
The given reaction equation is as follows.
Now, the two half-reactions can be written as follows.
Reduction half-reaction: 
This will be balanced as follows.
... (1)
Oxidation half-reaction: 
This will be balanced as follows.
... (2)
Adding both equation (1) and (2) we will get the resulting equation as follows.
Thus, we can conclude that coefficients for the given reaction species are 1, 6, 2, 3.
Initial Conditions:
Volume= v1= 417 cm³
Temperature= T1 = 278 K
Final Conditions:
Temperature= T2 = 231K
Volume = v2 =?
Use the general gas equation;
P1*v1/T1 = P2*v2/T2
As, the temperature is constant;
So,
v1/T1 = v2/T2
417/278 = v2/231
v2= 346.5 cm³
Answer:
₂He⁴
Explanation:
Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4 and atomic number less than 2 as compared to parent atom the starting atom.
Properties of alpha radiation:
Alpha radiations can travel in a short distance.
These radiations can not penetrate into the skin or clothes.
These radiations can be harmful for the human if these are inhaled.
These radiations can be stopped by a piece of paper.
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy
