Answer:
Explanation:
When group 7 elements react , their atoms gains one electron into their highest occupied energy level ( outer shell) to form single negative - charged ion .
As you move down the group , the outer shells get increased i.e an additional electron shell is added thereby increasing the atomic radius of the atom. The electrons in the outer shell move further away from the nucleus as we go down the group .
Therefore the force of attraction between the shells and nucleus is decreased .
This makes attracting an extra electron difficult . And so ability of the atom to attract electron to fill the outermost shell reduces which means the reactiveness of the atom reduces.
Models help scientists to make predictions about complex systems. Some models are something that you can see or touch. ... Climate models can predict how climate will change as certain gases are added to the atmosphere. To test how good a model is, scientists might start a test run at a time in the past.
Answer:
The mass of 3.491 × 10¹⁹ molecules of Cl₂ of Cl₂ is 4.11 × 10⁻³ grams
Explanation:
The number of particles in one mole of a substance id=s given by the Avogadro's number which is approximately 6.023 × 10²³ particles
Therefore, we have;
One mole of Cl₂ gas, which is a compound, contains 6.023 × 10²³ individual molecules of Cl₂
3.491 × 10¹⁹ molecules of Cl₂ is equivalent to (3.491 × 10¹⁹)/(6.023 × 10²³) = 5.796 × 10⁻⁵ moles of Cl₂
The mass of one mole of Cl₂ = 70.906 g/mol
The mass of 5.796 × 10⁻⁵ moles of Cl₂ = 70.906 × 5.796 × 10^(-5) = 4.11 × 10⁻³ grams
Therefore;
The mass of 3.491 × 10¹⁹ molecules of Cl₂ of Cl₂ = 4.11 × 10⁻³ grams.
The answer is D. Because most islands have dormant volcanoes
