Answer:
1. The first three Hydrogen atoms have the same number of protons
2. The first three Hydrogen atoms are also isotopes of each other
3. The third Hydrogen atom and the first Helium atom have the same mass number
4. The second Carbon atom and the first Oxygen atom both have the same number of neutrons
Explanation:
1. The number on the top left tells us the mass number while the bottom left number tells us the atomic number. The atomic number is equal to the number of protons.
2. An isotope is when there is an equal amount of protons, but a different number of neutrons. Neutrons can be calculated by taking the mass number and subtracting the atomic number.
3. As said before, the mass number is the number on the top left of each symbol. Look for atoms with the same mass number.
4. Neutrons can be calculated by taking the mass number and subtracting the atomic number. The second Carbon atom and the first Oxygen atom both have six neutrons. 14 - 6 = 8 neutrons for the second Carbon and 16 - 8 = 8 neutrons for the first Oxygen atom.
Answer:
The true statement about the discovery of electrons is :
C. Electrons were discovered in a vacuum tube
Explanation:
In 1870, Sir William Crookes developed the first cathode ray tube which have high vacuum inside.
These rays moved the paddled wheel when placed in their path.This means these rays have some momentum.
When the magnetic field was applied to the cathode rays they showed deflection. This means these cathode rays must have some charge because only charged particles can show deflection when place in magnetic field.
Later is was found by J.J Thomson that these are negatively charged.
How ?
We Know that like charges repel each other and unlike charges attract each other. This means if a particle has negative charge then it will attract the positive charge.
J.J Thomson studied these cathode ray tubes and found that these rays repels the negative charge particles .Hence these rays must be negatively charged.
He called these tiny Particle "electron"
The answer is c. more mass transportation in the cities
Heat energy is calculated by multiplying the mass, specific heat capacity of a substance by the change in temperatures. Therefore,the heat lost by water will be given by mass of water (in kg) × specific heat capacity of water × change in temperature. This heat will be equivalent to the heat gained by the spoon calculated by mass of the spoon by specific heat capacity by change in temperature. (considering that the specific heat capacity of gold is 125.6 J/kg/k)
hence, 0.05 kg × 49 × 125.6 J/kg/k = 307.72 Joules
therefore, heat lost by water is equivalent to 307.72 Joules