<u>Answer:</u> The mass of 1 mole of lithium is 6.941 grams.
<u>Explanation:</u>
To calculate the mass of a compound or element, we use the formula used to calculate the number of moles:

Where,
Number of moles of lithium = 1 mole
Given mass of lithium = ? g
Molar mass of lithium = 6.941 g/mol
Putting value in above equation, we get:

Hence, the mass of 1 mole of lithium is 6.941 grams.
Octane is the resistance of the burning of gasoline
Answer:
<em>All of the carbon-carbon bonds have exactly the same lengths - somewhere between single and double bonds. There are delocalized electrons above and below the plane of the ring. The presence of the delocalized electrons</em>
Explanation:
hope it helps
Answer:
The root mean square speed of O2 gas molecules is
<u>519.01 m/s</u>
<u></u>
Explanation:
The root mean square velocity :



Molar mass , M
For He = 4 g/mol
For O2 = 2 x 16 = 32 g/mol
O2 = 32/1000 = 0.032 Kg/mol
First calculate the temperature at which the K.E of He is 4310J/mol
K.E of He =


K.E of He = 4310 J/mol


<u>Now , Use Vrms to calculate the velocity of O2</u>




These atoms and other atoms in group 8A have constant valence shell.it means that all of them have 8 electrons in their valence shell (except helium that has only 2 electrons )and they don't want to attract electrons.
that s why they don't have electronegativity.
hope this helps