If a motionless object has a weight of 25 n, what is true of the normal force acting on the object? a. it is 25 n and acts in the same direction as the weight. b. it is 25 n and acts in the opposite direction to the weight. c. it is less than 25 n and acts in the opposite direction to the weight. d. it is more than 25 n and acts in the opposite direction to the weight.

B. normal contact force acts in the opposite direction as of weight, hence A is out. C is out as if normal contact force is lesser than the weight, the object would be sinking into the ground due to net force of the weight. D is out as if normal contact force is greater than the weight, the object would be flying upwards.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g