Answer:
0.196 M
Explanation:
First, we have to calculate the moles of sodium hydroxide.
moles = mass / molar mass
moles = 3.9280 g / (39.997 g/mol) = 0.098207 mol
It is important to realize that even though 300 mL is the volume of water firstly added to dissolve the hydroxide, the flask is then filled to the mark, meaning that the volume of the solution is 500 mL = 0.500 L.
The molar concentration of sodium hydroxide is:

The concentration is an intensive property, that is, it does not depend on the amount of matter. As a consequence, the concentration of the 50 mL of solution in the buret is the same as the concentration in the flask.
Answer: orientation , energy , frequency
Explanation:
According to the collision theory , the number of collisions that take place per unit volume of the reaction mixture is called collision frequency. The effective collisions are ones which result into the formation of products.
Effective collisions depends on the following two factors:-
1. Orientation factor: The colliding molecules must have proper orientation at the time of collision to result into formation of products.
2. Energy factor: For collision to be effective, the colliding molecules must have energy more than a particular value called as threshold energy.
Answer: B,C,D
Explanation: Who ever reads this have a great day and stay safe :}