Answer: 0.077 M
Explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time taken for decay process = 10 minutes
a = initial amount of the reactant= 0.859 M
a - x = amount left after decay process =?
Putting values in above equation, we get:


Thus the concentration of a after 10.0 minutes is 0.077 M.
Answer:
The sphere is positively charged
Explanation:
This is because when the positively charged rod is brought near the metal rod A, the electrons in metal rod A and sphere B are attracted towards it into metal rod A while the positive charges in the are repelled into sphere B. So, when the charged rod is withdrawn, and metal rod A and sphere B are separated, metal rod A is now negatively charged, but sphere B is positively charged.
So, sphere B is positively charged.
Answer:
Equal to 5000N
Explanation:
The stress on the material is defined by force per unit of cross-sectional area. So it depends on the force and the diameter of the wire, which is the same for both wires. The material that defines the breaking point, is also the same. Therefore, both wires have their breaking point the same at 5000N. The wire length plays no role in here.
When you talk about rate, you will expect that it will be in terms of a time unit. It measures how fast it is going. So, you would expect that the denominator is in time units. For the movement, you can measure this with either distance or velocity.
So, for the first variety, you would need distance and time to measure the rate of how far you go at a certain time. It is also called as velocity. For the second variety, you would need velocity and time to measure the rate of how fast you are going at a certain interval. It is also called as acceleration.