Answer : The number of molecules present in nitrogen gas are, 
Explanation :
First we have to calculate the moles of nitrogen gas by using ideal gas equation.
where,
P = Pressure of 
gas = 
(1 atm = 760 mmHg)
V = Volume of gas = 985 mL = 0.982 L (1 L = 1000 mL)
n = number of moles = ?
R = Gas constant = 
T = Temperature of gas = 
Now put all the given values in above equation, we get:
Now we have to calculate the number of molecules present in nitrogen gas.
As we know that 1 mole of substance contains 
number of molecules.
As, 1 mole of gas contains number of molecules
So, 
mole of gas contains 
number of molecules
Therefore, the number of molecules present in nitrogen gas are,
The last one, answer is D
Answer:
protons = atomic numbermass number = protons + neutronsatomic number = mass number - neutrons = 78-38 = 40
Explanation:
Answer: The transition elements are in the d-block, and in the d-orbital have valence electrons. They can form several states of oxidation and contain different ions. Inner transition elements are in the f-block, and in the f-orbital have valence electrons.
Explanation:
Filter flasks are
also known as vacuum, suction or the Buchner flasks. They have thick walls and also
have a short glass tube. The thick walls are designed to enable the filter withstand
high pressures of vacuum applied to filter substances. Generally this is used
for filtering.
While the Erlenmeyer flask
also called as a conical flask, is a titration flask which consists of a
conical body, a flat bottom, and round neck. This is used for used for general
uses such as mixing, titrations, preparation of cultures, for
recrystallization, and for supporting filter funnels.
<span>Lastly, the Volumetric flasks are graduated flasks which having markings
for different volumes. They are calibrated accurately for a specific amount of
liquid that can be contained in it hence this is specially used for storing
precise amounts of liquid. </span>
