Answer:
276 days
Explanation:
1/4 th of the original means <u><em>2 half lives</em></u>
1 half life = 138 days
So,
2 half lives = 276 days
Answer:

Explanation:
Given the parallex of the star is 0.1 sec.
The distance is inversely related with the parallex of the star. Mathematically,

Here, d is the distance to a star which is measured in parsecs, and P is the parallex which is measured in arc seconds.
Now,

And also know that,

Therefore the distance of the star is
away.
Answer:
South = 1.5m
West =4.2m
Explanation:
Kindly see attached a rough draft of the situation
Step one
Given data
From the sketch the direction of the player is along the resultant of the triangle, corresponding to the Hypotenuse
Step two:
Hence for an opponent to tackle him towards the south, he must be at
sin θ= opp/hyp
sin 20=x/4.5
x=sin 20*4.5
x=0.342*4.5
x= 1.5m
Also, for an opponent to tackle him towards the south, he must be at
cos θ= adj/hyp
cos 20=y/4.5
y=cos 20*4.5
y=0.93*4.5
y= 4.2m
If i thought about this properly the answer is b
Electrons that are the highest energy level is called Valence Electrons