1. Decreases by 4. (B)
2. The atomic number changes. (B)
3. 56/26 Fe. (C)
4. Potassium-40;t1/2=25 days. (B)
5. Takes place in the upper atmosphere. (A)
Answer: The bond between boron and hydrogen in boron trihydride is covalent bond.
Explanation:
The type of bonding between the atoms forming a compound is determined by using the electronegativity difference between the atoms. According to the pauling's electronegativity rule:
- If
, then the bond is non-polar. - If
, then the bond will be covalent. - If
, then the bond will be ionic.
We are given:
Electronegativity for boron = 2.0
Electronegativity for hydrogen = 2.1
As, 
is less than 1.7 and not equal to 0. Hence, the bond between boron and hydrogen is covalent bond.
Answer:
1. Not to have enough salt water on the foil
2.not cleaning the foil well to remove interfering materials
Answer:
b. 0.50 moles
Explanation:
To solve this problem we use <em>Avogadro's number</em> (6.023x10²³ atoms/mol).
By <u>dividing the number of atoms (or molecules) by that number</u>, we can calculate how many moles they represent.
- 3.01x10²³ atoms ÷ 6.023x10²³ atoms/mol = 0.50 moles
So the answer is option b. 0.50 moles.
