The answer is A .
<span>Rusting of iron. combustion (burning) of wood. metabolism of food in the body. mixing an acid and a base, such as hydrochloric acid (HCl) and sodium hydroxide (NaOH) .</span>
Answer:

Explanation:
The capacitor of a parallel-plate capacitor is given by:

where
A is the area of each plate
d is the separation between the plates
is the vacuum permittivity
The energy stored in a capacitor instead is given by

where
Q is the charge stored in each plate
Substituting the expression we found for C inside the last formula,

And re-arranging it

Now if we substitute

We find the charge stored on the capacitor:

Answer:
vi) Double the current in the wire, and double the number of turns in the 20-cm long solenoid
Explanation:
The magnetic field inside the solenoid and the current flowing in the coil of solenoid are related to each other by the following equation
B₀=μ₀nI₀
Where,
B₀ is the magnetic field in the middle of solenoid
n is the number of turns in the coil of solenoid
I₀ is the current flowing in the coil of solenoid
In the above equation, as μ₀ is a constant so the magnetic field will be directly proportional to the number of turns multiplied by the current. So, changing the radius of the coil or length of the coil will have no effect on the magnetic field.
As we have to increase the magnetic field by 4 times, we need to double the current as well as the number of turns as mentioned in the option vi.
Answer:
6 meters away
Explanation:
6*1.4= 8.4 which is pretty close
<span>So we want to know what kind of wave is the scientist is studying while studying earthquakes. Waves that produce earthquakes are mechanical waves. Gamma rays and radiowaves are both electromagnetic waves and don't require a medium but mechanical do. So the correct answer is mechanical waves.</span>