Questions

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

Because arteries have to have thick walls for use of protection. Its when you get to veins where the walls get thinner. And the use of the heart is to pump blood to all of the cells and organs in the body so it would be to transport blood away from the heart.

i.e. 

Arteries = Away from the Heart 
Veins = Back to the Heart.

Lithium is the lightest of all the metals due to its low atomic number among meetals

From the given data,

1 + 9 + 8 = 1

ONE + NINE + EIGHT

Consider the first letters and join them viz O N E = 1

So, now consider 2 + 8 + 9 in similar way

TWO+EIGHT+NINE

First letters are T E N = 10

2 + 8 + 9 = 1⃣0⃣