There will be 7.5 g of Be-11 remaining after 28 s.
If 14 s = 1 half-life, 28 s = 2 half-lives.
After the first half-life, ½ of the Be-11 (15 g) will disappear, and 15 g will remain.
After the second half-life, ½ of the 15 g (7.5 g) will disappear, and 7.5 g will remain.
In symbols,
<em>N</em> = <em>N</em>₀(½)^<em>n</em>
where
<em>n</em> = the number of half-lives
<em>N</em>₀ = the original amount
<em>N</em> = the amount remaining after <em>n</em> half-lives
The acceleration is defined by force divided by the mass of the object. So, When the smaller object is hit by a small force, it can produce equal acceleration which is same as that of the bigger body hit with large force.
<h3><u>Explanation:</u></h3>
Force is defined as the product of the mass of the body its applied to and the acceleration of the body in the direction of the force. So acceleration is force divided by the mass of the body.
Let the mass of the smaller body be m and that of the larger body be M.
The smaller force applied on the smaller body be f and the larger force applied on the larger body be F.
So acceleration of the larger body = F/M.
Acceleration of the smaller body = f/m.
For the accelerations to be same,
F/M = f/m.
Or F/f = M/m.
So when the ratio of the force applied on two bodies is in ratio of their masses, the acceleration becomes equal.
Answer:
What is most widely accepted today is the giant-impact theory. It proposes that the Moon formed during a collision between the Earth and another small planet, about the size of Mars. The debris from this impact collected in an orbit around Earth to form the Moon.
Explanation:
Answer is: 3,94 of hydrogen gas.
Chemical reaction: 2K + 2HBr → 2KBr + H₂.
n(K) = 9,87 mol.
n(H₂) = ?.
from reaction: n(K) : n(H₂) = 2 : 1.
9,87 mol : n(H₂) = 2 : 1
n(H₂) = 4,935 mol for 100% yield of reaction
n(H₂) = 4,935 · 0,798 = 3,94 mol for 78,9 % yield of reaction.
n - amount of substance
