Explanation:
No because the person on the bike is going faster then the person on foot.
B. Sand.
Sand would definitely increase friction because of the roughness of it surface. When its surface comes with another rough surface it would tend to increase friction. All other options given tend to reduce friction one way or the other.
Answer: solid
Explanation: Chemical reactions are those which involve rearrangement of atoms.
Chemical changes are accompanied by following changes:
1) Absorption or release of heat
2) Change in color
3) Formation of gas bubbles
4) Formation of a solid product called as precipitate
Example of formation of precipitate or solid in chemical reaction:
Resistance of a material being scratched in known as: Hardness
Answer:
the initial concentration of SCN- in the mixture is 0.00588 M
Explanation:
The computation of the initial concentration of the SCN^- in the mixture is as follows:
As we know that

As it is mentioned in the question that KSCN is present 10 mL of 0.05 M
So, the total milimoles of SCN^- is
= 10 × 0.05
= 0.5 m moles
The total volume in mixture is
= 45 + 10 + 30
= 85 mL
Now the initial concentration of the SCN^- is
= 0.5 ÷ 85
= 0.00588 M
hence, the initial concentration of SCN- in the mixture is 0.00588 M