Answer:Group, in chemistry, a column in the periodic table of the chemical elements. In a group, the chemical elements have atoms with identical valence electron counts and identical valence vacancy counts. ... Groups are numbered from 1 to 18.
Explanation:Hope this helped u may i also get brainlist plz only if u wanna give me brainlist though have an great day!
<span>( 2257 J/g) x (18.0 g) = 40626 J</span>
Recrystallization of a solid is an experimental technique used to separate out impurities from a pure product using differential solubilities of the solids in a solvent at different temperatures. We chose a solvent in which the pure solid has lower solubility at low temperatures but is completely soluble at higher temperatures. The amount of solvent taken must be sufficient to completely dissolve the impure solid formed in a reaction. The impurities must be soluble in cold solvent, so that they can remain in solution after crystallization of pure compound. When the amount of solvent is too little then we cannot achieve the separation of pure crystals as the pure solid crystallizes on the impurities.
So the correct answer will be the crystals form with product coated onto impure crystals
<u>Answer:</u> The moles and mass of oxygen gas needed to react is 4.175 moles and 133.6 grams
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
.....(1)
Given mass of ammonia = 56.8 g
Molar mass of ammonia = 17 g/mol
Putting values in equation 1, we get:
For the given chemical equation:
By Stoichiometry of the reaction:
4 moles of ammonia reacts with 5 mole of oxygen gas
So, 3.34 moles of ammonia will react with = of oxygen gas
Now, calculating the mass of oxygen gas from equation 1, we get:
Molar mass of oxygen gas = 32 g/mol
Moles of oxygen gas = 4.175 moles
Putting values in equation 1, we get:
Hence, the moles and mass of oxygen gas needed to react is 4.175 moles and 133.6 grams
Answer:
Populations have genetic variation.
The environment changes.
Organisms must have specific traits in order to survive and reproduce.
Explanation:
Natural selection is a phenomenon whereby organisms better adapted to their environment are able to survive due to this phenotypic capability.
- Natural selection provides an advantage during an adverse condition for organisms that have a rich genetic variation in their population.
- Also, environmental changes induces natural selection whereby organisms must adapt to changes around.
- For organisms to survive, they must have specific traits that gives them a competitive reproductive advantage.