Answer:
E = 0.437 N/C
Explanation:
Given that,
Charge, 
Electric force, 
Let the strength of the electric field is E. We know that, the electric force is given by :
F = qE
Where
E is the electric field strength

So, the strength of the electric field is equal to 0.437 N/C.
Answer:
The velocity is 
Explanation:
From the question we are told that
The first distance is 
The first speed is 
The second distance is 
The second speed is 
Generally the time taken for first distance is



The time taken for second distance is



The total time is mathematically represented as

=> 
=> 
Generally the constant velocity that would let her finish at the same time is mathematically represented as

=> 
=> 
Answer: B
Explanation:
The reactivity of alkaline metal ( example group one ) increases down the group because of the increase in atomic mass from the top to the bottom of the group. As the mass increases, the force between the nucleus and the valence electron gets weaker and the atom will easily give up the electron as a result of this which eventually increases its reactivity.
The reactivity of halogens decreases as atomic mass increases. Therefore, option B is the correct answer.
The objects density is greater than one