I think the correct answer would be the third option. From the physical change that happened, we can only tell that the mass of the plastic would be still the same and would weigh 15 grams. This is in accordance with the Law of conservation of mass where it states that mass cannot be destroyed or created. So, since it is only a physical change that happens the substance itself would still be the same and it is only the form that is changed, it would still have the same mass. However, with the change, the volume is changed and is said to increase which means it would greatly affect the density. Increasing the volume would result to a decrease in density.
<u>Answer:</u> The moles of oxygen and carbon dioxide in air is 
and 
respectively
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
Given mass of atmosphere = 
Average molar mass of atmosphere = 28.96 g/mol
Putting values in above equation, we get:
We know that:
Percent of oxygen in air = 21 %
Percent of carbon dioxide in air = 0.0415 %
Moles of oxygen in air = 
Moles of carbon dioxide in air = 
Hence, the moles of oxygen and carbon dioxide in air is and respectively
Answer:
F
Explanation:
When an atom lose or gain electrons ions are formed.
There are two types of ions. Cation and anion.
Cation:
Cations are formed when atom lose electrons. For example:
X → X⁺ + e⁻
Anion:
It is formed when an atom gain electrons. For example:
X + e⁻ → X⁻
Fluorine is present in group seventeen. It has seven valance electrons. It gain one electron to complete the octet and form anion with charge of -1.
Calcium is alkaline earth metal. It is present in group two it loses two valance electrons and form cation with charge of +2.
Neon is noble gas. It already have complete octet. It can not form ions. To remove the electrons from noble gases very high temperature is required.
Zinc is present in group 12. It usually form cation by losing its two valance electrons but it can also show oxidation state -2.
HCl is considered as polar molecule and that is incorrect answer, The choices provided are A) HCl , B) CH₄ , C) H₂O, D) NH₃
And the correct answer is : B) CH₄
In case of H₂O and NH₃ the high difference in electronegativity between nitrogen or oxygen and hydrogen make the bonds acquire partial charges and become polar while in case of CH₄ the difference in electronegativity between carbon and hydrogen is only 0.4 so it considered as non-polar bond
also carbon connected from all directions with Hydrogens
