Answer:
Hydrogen was discovered by the English physicist Henry Cavendish in 1766
Explanation:
Scientists had been producing hydrogen for years before it was recognized as an element. Written records indicate that Robert Boyle produced hydrogen gas as early as 1671 while experimenting with iron and acids.
Answer: Time taken by a sound impulse to travel through an aluminum rod 25 kilometers long is 4.9 seconds.
Solution:
Length of aluminium rod = 25 km = 25000 m (1 km=1000 m)
Time taken by sound to travel through aluminium = 5100 m/s (from the table given)
time taken =
Hence, the correct option is 4.9 seconds.
1. Has 4 sig figs, all non zeros are significant
2. 3 sig figs trailing zero after a decimal
3. 3 sig figs
Answer:
0.9 moles of water
Explanation:
Use mole ratios:
5 : 6
divide by 5 on both sides
1 : 1.2
multiply by 0.75 on both sides
0.75 : 0.9
So the result is 0.9 moles of water
(Please correct me if I'm wrong)
