Arctic Circle, Tropics of cancer, Equator, Tropics of Capricorn, Antarctica Circle,prime meridian
Answer:
A Binary Star System is a star system consisting of only two stars orbiting around a common center.
Answer: The rock is 2000785 years old.
Explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = age of sample
a = initial amount of the reactant = 800
x = amount of daughter isotope = 600
a - x = amount left after decay process = amount of parent isotope = (800-600) = 200
Half life is the amount of time taken by a radioactive material to decay to half of its original value.




The rock is 2000785 years old.
Answer:
diaphragm,cervical cap,male condom, female condom, spermicide foam sponges and film.
Explanation:
unlike other methods of birth control, barrier methods are used only when you have sexual intercourse .
'Climatic variations' and 'Human activities' can be regarded as the two main causes of desertification. removal of the natural vegetation cover(by taking too much fuel wood), agricultural activities in the vulnerable ecosystems of arid and semi-arid areas, which are thus strained beyond their capacity.