Answer:
D. They have the same number of valence electrons
Explanation:
In order to answer this question we need to understand the following.
- Valence electrons refers to the outermost electron(s) in the outermost energy level of an atom.
- Elements in the same group in the periodic table have the same number of valence electrons. For instance, group 2A elements have 2 valence electrons.
- The reactivity of elements in the periodic table is based on the number of valence electrons and the ease of gaining or losing electrons.
- Elements in the same group have similar valence electrons and therefore share similar chemical properties such as reactivity.
- Hence, elements in the same group have same number of valence electron and will thus have similar reactivity.
The speedometer displays the speed, rather than the velocity of the car. Velocity is usually displayed by a GPS unit, and may be in the for of- 22 Mph
at a heading of 355 degrees. A speedometer actually uses the rpm of the wheels to calculate speed, which is why if you put your car's tires off the ground and rev the engine, the displayed speed increases even though you are not going anywhere.
The energy needed the raise the temperature of the block of silver is given by:
where m is the mass of the block, Cs the specific heat capacity of silver and
its increase in temperature.
Using the numbers of the problem, we find
Answer:
I = 6 A
Explanation:
Given that,
Power of an electric heatr, P = 1.38 kW
The voltage of the mains supply, V = 230 V
We need to find the current through the heater. The electric power in terms of voltage and current is given by :
So, the current through an electric heater is 6 A.
