Answer:
Answers below (just some ethics)
Explanation:
Bad= Earthquake activity causing damage in a major city.
Bad= Producing and emitting smog from a smokestack.
Good= Planting native bushes to help control erosion.
Good= Volcanic eruption resulting in the formation of an island.
Answer:
OPTION (A) : Testing a rock sample for gold content
Explanation:
For testing a rock sample of gold content you will need a Chemist. To test the material, the sample is rubbed on black stone which will leave a mark on the stone. This mark is tested by applying aqua fortis i.e nitric acid on the mark. If the mark gets dissolve then the material is not gold. If the mark sustain the it is further tested by applying aqua regia i.e nitric acid and hydrochloric acid which will prove the sample is of gold if it gets dissolve on using hydrochloric acid. The purity of the sample can be checked by differing the concentration of the aqua regia and comparing it with the gold material of the known purity.
Answer:
D = 5.3 g/mL
Explanation:
Density = Mass over Volume
D = m/V
Step 1: Define
D = unknown
m = 16 g
v = 3.0 mL
Step 2: Substitute and Evaluate
D = 16 g / 3.0 mL
D = 5.333333333 g/mL
Step 3: Simplify
We have 2 sig figs.
5.333333333 g/mL ≈ 5.3 g/mL
Explanation:
Bohr built on Nicholson's idea by adopting the requirement that the angular momentum can have only certain discrete values related to Planck's constant. However Bohr's atom has many orbits for the electrons.