Impulse = change of momentum
Impulse = 45 x 6 = 270 Ns
Answer:

Explanation:
= normal force acting on the coin
Normal force in the upward direction balances the weight of the coin, hence

= frequency of rotation
Angular velocity of turntable is hence given as

= distance from the axis of rotation
= minimum coefficient of static friction
static frictional force is given as

The static frictional force provides the necessary centripetal force , hence
Centripetal force = Static frictional force

I do not agree with the statement.
The "substance" can be a compound. It's "pure"
as long as there's nothing else in it but its name.
'Pure' water is 100% H₂O with nothing else in it.
'Pure' table salt is 100% NaCl with nothing else in it.
'Pure' carbon dioxide is 100% CO₂ with nothing else in it.
These example substances are all compounds, not elements.