Answer : The mass of ammonia present in the flask in three significant figures are, 5.28 grams.
Solution :
Using ideal gas equation,

where,
n = number of moles of gas
w = mass of ammonia gas = ?
P = pressure of the ammonia gas = 2.55 atm
T = temperature of the ammonia gas = 
M = molar mass of ammonia gas = 17 g/mole
R = gas constant = 0.0821 L.atm/mole.K
V = volume of ammonia gas = 3.00 L
Now put all the given values in the above equation, we get the mass of ammonia gas.


Therefore, the mass of ammonia present in the flask in three significant figures are, 5.28 grams.
The atomic number,atomic mass,valence electrons and the formula for calculating the number of neutrons is also given.The following table has been completed below in the attachment.
Explanation:
Atomic Number:the number of protons /electrons present in the nucleus of an atom is called the atomic number.
Mass Number/Atomic Mass:the number of protons and neutrons present in a nucleus
<u>Example:</u>
;here;6 implies the atomic number and 12 implies the mass number/atomic mass
<u><em>No.of neutrons=Mass number-Number of protons</em></u>
Valence electrons:the number of electrons present in the outer most shell of an atom are called valence electrons
<u>Example:</u>If we consider a carbon atom;as its <em>e</em><em>lectronic configuration is2,4 and</em> it belongs to 4th group.Therefore the number of valency electrons in carbon is <u>4.</u>
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Answer:
The reaction will be spontaneous
Explanation:
To determine if the reaction will be spontaneous or not at this temperature, we need to calculate the Gibbs's energy using the following formula:
<u>If the Gibbs's energy is negative, the reaction will be spontaneous, but if it's positive it will not.</u>
Calculating the
:
Now, other factor we need to determine is the sign of the S variation. When talking about gases, the more moles you have in your system the more enthropic it is.
In this reaction you go from 7 moles to 8 moles of gas, so you can say that you are going from one enthropy to another higher than the first one. This results in:
If the variation of S is positive, the Gibbs's energy will be negative always and the reaction will be spontaneous.
Answer:
<em>Alkali metals are among the most reactive metals. This is due in <u>part to their larger atomic radii and low ionization energies.</u> They tend to donate their electrons in reactions and have an oxidation state of +1. ... All these characteristics can be attributed to these elements' large atomic radii and weak metallic bonding.</em>
Explanation:
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