The radiator is next to the triangle, receiving the sound waves and they travel through the radiator up to the other room. She can't hear the sound if the triangle isn't struck near the radiator because the sound waves aren't going through the radiator, and are not able to reach her through the wall. Hope this helps!
Answer:
A
Explanation:
because number of particle = moles × 6.02 × 10^23
which gives the answer as an A
