Answer:
Francium (Fr)
Explanation:
Looking at the periodic table, Francium has 7 energy levels as it is in the 7th Period and is in the 1st Group (meaning it has one electron in the outermost shell) which suggests that it has one valence electron.
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Answer:
Empirical formula is NH₃
Explanation:
Given data:
Percentage of hydrogen = 82%
Percentage of nitrogen = 18%
Empirical formula = ?
Solution:
Number of gram atoms of H = 18 / 1.01 = 17.8
Number of gram atoms of N = 82 / 14 = 5
.9
Atomic ratio:
H : N
17.8/5.9 : 5.9/5.9
3 : 1
H : N = 3:1
Empirical formula is NH₃
Gases from a dead star gather and contract statement describes the formation of a nebula.
<u>Option: D</u>
<u>Explanation:</u>
- A nebula is a massive cloud of spatially dust and gas. Many nebulae derive from the gas and dust pushed out by a dying star's eruption, like a supernova. Other nebulae are environments where the formation of new stars begins.
- Five forms of cloudy or nebulous celestial bodies are planetary nebulae, emission nebulae, transparent nebulae, supernova remnants and dark nebulae.
- The He and H are predominantly responsible for dust and gases, which are widespread but gravity can begin to pull around each other clusters of dust and gas gradually.
- As these clusters grow bigger and bigger, their gravity becomes better and better. The clump of dusts and gases finally becomes so heavy that it drops from its own gravity.