Answer:
Magnesium and strontium
Explanation:
11 protons and 11 electrons, 12 neutrons.
The atomic number of sodium is 11, therefore the number of electrons and protons are 11. The atomic mass is 23, and to find neutrons you need to subtract the atomic number from the atomic mass, therefore the number of neutrons are 12.
UV exposure that leads to sunburn is proven in developing melanoma, the most dangerous of the three most common types of skin cancer.
Answer:- b. +3
Explanations:- Charge of a metal ion is equal to the number of valence electrons it has as it loses these electrons to have its nearest noble gas like electron configuration.
Al has 3 valence electrons and being a metal it loses all of these and so the charge of Al ion is +3. It could be shown as:
So, the right choice is b. 3+.
Answer:
87.3 calories of heat is required.
Explanation:
Heat = mcΔT
m= mass, c = specific heat of silver, T = temperature
H= 57.8 g * 0.057 cal/g°C * ( 43.5 - 17 °C)
H = 57.8 * 0.057 * 26.5
H = 87.3069 cal.
The heat required to raise the temperature of 57.8 g of silver from 17 °C to 43.5 °C is 87.3 calories.
Answer:
A meteor is an asteroid or other object that burns and vaporizes upon entry into the Earth's atmosphere; meteors are commonly known as "shooting stars." If a meteor survives the plunge through the atmosphere and lands on the surface, it's known as a meteorite.
Explanation:
