The answer is c. +2.0 µC
To calculate this, we will use Coulomb's Law:
F = k*Q1*Q2/r²
where F is force, k is constant, Q is a charge, r is a distance between charges.
k = 9.0 × 10⁹ N*m/C²
It is given:
F = 7.2 N
d = 0.1 m = 10⁻¹ m
Q1 = -4.0 µC = 4 * 1.0 × 10⁻⁶ = 4.0 × 10⁻⁶
Q2 = ?
Thus, let's replace this in the formula for the force:
7.2 = 9.0 × 10⁹ * 4.0 × 10⁻⁶ * Q2/(10⁻¹)²
7.2 = 9 * 4 * 10⁹⁻⁶ * Q2/10⁻¹°²
7.2 = 36 × 10³ * Q2 / 10⁻²
Multiply both sides of the equation by 10⁻²:
7.2 × 10⁻² = 36 × 10³ * Q2
⇒ Q2 = 7.2 × 10⁻² / 36 × 10³ = 7.2/36 × 10⁻²⁻³ = 0.2 × 10⁻⁵ = 2 × 10⁻⁶
Since µC = 1.0 × 10^-6:
Q2 = 2 * 1.0 × 10^-6 = 2 µC
Explanation:
It is known that energy balance relation is as follows.

Also, 
so,
According to the ideal gas equation,

Putting the values into the above equation as follows.

= 
= 693.3 R
Now, we will convert the temperature into degree Fahrenheit as follows.
693.3 - 458.67
= 
From table A-
= 0.240 Btu/lbm R and
= 0.171 Btu/lbm
Now, we will substitute the energy balance as follows.
= 
= 59.3 Btu
Thus, we can conclude that final temperature of air is 59.3 Btu.
Answer:
hi there!!
Explanation:
Nickel 149 pm
Cobalt 152 pm
Calcium 194 pm
Potassium 243 pm
So Potassium is the correct answer