Questions

Starting with the top 3 digit number, the first digit increases by 2 as you descend,from 1 to 11. The middle digit decreases by 1 each time,and the right hand digit alternates between 5 and 3

1.Hardware abstraction layer

2.Kernel

3.Subsystems

4.System Services.

Ragini

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