Answer:
change in the total mass of substances
Answer : Option 1) nuclei of 
and nuclei of 
only.
Explanation : Radiation is spontaneously emitted from nuclei of 
because this isotope of hydrogen is highly radioactive as compared to other isotopes of hydrogen namely; nuclei of and nuclei of .
They have much stable nucleus as compared to nuclei of .
The more it is unstable the more radiations will be emitted from its nucleus.
Answer:
Explanation:
GIven that:
The activation energy = 250 kJ
k₁ = 0.380 /M
k₂ = ???
Initial temperature 
1001 K
Final temperature 
298 K
Applying the equation of Arrhenius theory.
where ;
R gas constant = 8.314 J/K/mol
/M .sec
Half life:
At 1001 K.
1.82368 secc
At 298 K:
Answer:
The shape of the BF3 molecule is best described as trigonal planar.
Explanation:
The Lewis Structure for BF3 is like this:
_ _
| F | | F |
\ /
B
|
| F |
---
It forms three angles of 120° each. The bonds are in the same planar that's why it is trigonal planar and they are exactly the same.
Boron and Fluorine have 3 covalent bonds, produced by electronic promotion that enables the 2py and 2pz orbitals, leaving an electron to pair in the 2px. So boron will have 3 possible electrons to pair in 2s1, 2px and 2py, remember that electronic configuration for B is 1s2, 2s2, 2p1
By hybridization between the orbitals 2s2 and 2p1, the electrons of F, can joined to make the covalent bond. The new B configuration is 1s2, 2s1, 2px1, 2py1 (these last three, hybrid orbitals)
