Answer:
0.14 lb
Explanation:
The <em>half-life</em> of U-235 (703.8 ×10⁶ yr) is the time it takes for half the U to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Amount
<u>half-lives</u> <u>t/(yr × 10⁶)</u> <u>remaining</u> <u>remaining/lb
</u>
1 703.8 ½ 1.1
2 1408 ¼ 0.55
3 2111 ⅛ 0.28
4 2815 ¹/₁₆ 0.14
We see that 2815 × 10⁶ yr is four half-lives, and the amount of U-235 remaining is 0.14 lb.
Answer:
Option C
Explanation:
According to Hund's rule
- pairing of electrons occur first in lower energy orbitals then in orbitals having higher energy.
d subshell has 5 orbitals.
- so first these 5 get filled.
- The. one will be added to first one.
Answer:
Explanation:
In beta emission, a neutron is converted into a proton thereby reducing the neutron:proton (N/P) ratio.
When a beta emission occurs, the mass number remains the same while the nuclear charge increases by one unit. The daughter nucleus is found one place to the right of its parent in the periodic table.
They are made up of chains of Hydrogen and c) Carbon
The balanced reaction is
Ca + 2H2O → Ca(OH)2 + H2
Here this reaction can be compared with
A + BC ---> AB + C
So here one reactant (A) is accepting a group which is being given by another compound (BC) however the A is not giving any group / element or ion
So this single displacement
Similarly in the given reaction
the anion OH- is only being replaced
The element Ca accepts OH- and H2O loses the same group to form new element H2
So the correct answer is
Single replacement also known as single displacement
