To identify which one is ionic compound, you would select the compound with the high melting point. Ionic compounds<span> have high </span>melting points<span> because the electrostatic interactions that hold the compounds together are very strong. Hope this answers the question.</span>
Answer:
Maximum height of the ball, h(t) = 27.56 m
Explanation:
It is given that, a ball is shot from the ground straight up into the air with initial velocity of 42 ft/sec.
The height of the ball as a function of time t is given by :

h₀ is initial height, h₀ = 0
So,
.........(1)
For maximum/minimum height, 
...(2)
t = 1.31 s
Differentiating equation (2) wrt t
h''(t) = -32 < 0
So, at t = 1.31 seconds we will get the maximum height.
Put the value of t in equation (1)

h(t) = 27.56 m
Hence, this is the required solution.
Answer:
E = 4.83 N/ C
Explanation:
If we have a uniform charge sphere we can use the following formulas to calculate the Electric field due to the charge of the sphere:
: Formula (1) To calculate the electric field in the region outside the sphere r ≥ a
Where:
K: coulomb constant (N*m²/C²)
a: sphere radius (m)
Q: Total sphere charge (C)
r : Distance from the center of the sphere to the region where the electric field is calculated (m)
Equivalences
1nC=10⁻⁹C
1cm= 10⁻²m
Data
k= 9*10⁹ N*m²/C²
Q=4nC=4 *10⁻⁹C
D = 26 cm = 26*10⁻²m = 0.26m
a = D/2 = 0.13m
r= R+a = 2.6 m+ 0.13m = 2.73m
Problem development
Magnitude of the electric field at r = 2.73m from the center of the sphere
r>a , We apply the Formula (1) :


E= 4.83 N/ C