Answer: D) protons.
The other option that would make the most sense would be electrons, however the mass of an electron is so small that is basically negligible, so it's not included in the atomic mass.
Answer no 1)
The correct option is A) He did not try to learn it. It was natural.
As Sergei did not put any effort in learning the art of tongue rolling, hence we can assume that this characteristic was found to be naturally present in Sergei. This hence shows that Sergei has acquired the characteristic of tongue rolling through inheritance.
Answer No 2)
We can learn whether other persons in the class have the characteristic of tongue rolling or not by observing them. In the students who can roll their tongue we can conduct a survey asking them whether they tried to learn the trait or did not put any effort to learn tongue rolling. The students who learned the skill by practicing might have acquired the characteristic from learning.
Answer No 3)
We can survey the class for features like eye color, hair color, height, weight. We can ask certain questions in our survey like whether the characteristic can be seen in either the mother, father or other siblings.
Answer:
0.57 moles (NH4)3PO4 (2 sig. figs.)
Explanation:
To quote, J.R.
"Note: liquid ammonia (NH3) is actually aqueous ammonium hydroxide (NH4OH) because NH3 + H2O -> NH4OH.
H3PO4(aq) + 3NH4OH(aq) ==> (NH4)3PO4 + 3H2O
Assuming that H3PO4 is not limiting, i.e. it is present in excess
1.7 mol NH4OH x 1 mole (NH4)3PO4/3 moles NH4OH = 0.567 moles = 0.57 moles (NH4)3PO4 (2 sig. figs.)"
Sublimation.
Since evaporation is liquid into gas, melting is solid into liquid and deposition is the geological process where sediments are added to land forms.
So in a chemical change, the product would loses its properties, would form new products and would not be easily reversed.
In a physical change, the products WILL NOT lose any of their properties, WILL NOT form any new products and WILL be easily reversed.
Talking about Water turning to ice I would say it’s all about physical change and not chemical change.
But I would suggest you to either make a research about it or ask your teacher :))