Answer:
Group 17 elements:
Flourine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (As).
Period 2 elements:
Lithium (Li), Beryllium (Be), Boron (B), carbon (C), Nitrogen (N), Oxygen (O), flourine (F), And Neon.
Answer:

Explanation:
1. Calculate the moles of CoF₂ needed

2. Calculate the mass of CoF₂

(3) It involves interactions between biotic and abiotic
factors.
Explanation:
An ecosystem involves the interaction between biotic and abiotic factors.
The biotic factors are the living components of the ecosystem. The abiotic factors are the non-living components.
An ecosystem is made up the interaction between living organisms and their environments.
- Ecosystem are combination of the community of lives and the environment.
- The environment contains the non-living abiotic components.
- The organisms are the living components.
- All of this merges together to form of the ecosystem.
learn more:
Ecosystem brainly.com/question/2456852
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Answer:
1.54×10^20 atoms
Explanation:
It's done by using the relation
N=n×L where,
N = number of entities present
n= amount of substance (mole)
L= Avogadro's constant which is 6.02×10^23
now from the question, given
n=0.000256
And L=6.02×10^23
N= 0.000256×6.02×10^23
N= 1.54×10^20 atoms