The answer should be B. hope this helped ;)
I don’t know about 3 but I know that 4 is solid, 5 is you’ll feel the vibration first, 6 is you’ll see the lightning first because the speed of light is faster than the speed of sound and 7 is sound waves need a medium to travel and light waves don’t, sound waves are longitudinal and light waves are transverse, and sound waves are mechanical waves while light waves are electromagnetic waves
Answer:
Option D. 230 J
Explanation:
We'll begin by calculating the temperature change of the iron. This can be obtained as follow:
Initial temperature (T₁) = 50 °C
Final temperature (T₂) = 75 °C
Change in temperature (ΔT) =?
ΔT = T₂ – T₁
ΔT = 75 – 50
ΔT = 25 °C
Thus, the temperature change of the iron is 25 °C.
Finally, we shall determine the amount of heat energy used. This can be obtained as follow:
Mass (M) = 20 g
Change in temperature (ΔT) = 25 °C
Specific heat capacity (C) = 0.46 J/gºC
Heat (Q) =?
Q = MCΔT
Q = 20 × 0.46 × 25
Q = 230 J
Thus, the amount of heat used was 230 J
Answer:

Explanation:
In a nuclear reaction, the total mass and total atomic number remains the same.
Am has an atomic number of 95. So correct reaction is:-
To calculate A:
Total mass on reactant side = total mass on product side
343 + 4 = A + 2
A = 345
To calculate Z:
Total atomic number on reactant side = total atomic number on product side
95 + 2 = Z + 0
Z = 97
Hence, the isotopic symbol of unknown element is 
Homogeneous because it is unable to be distinguished of the components Water and Salt