The mass number is the summation of number of proton and neutron present in a nucleus of an atom. For the neutral atom the number of positive charge (number of proton) must be equal to the number of electrons. The number of electrons present in an atom is the atomic number of the atom. The standard way to express the mass number (a) and atomic number (m) of a atom (say X) is 
. Now for silicon number of electron or atomic number is 14. And the mass number (a) given 29. Thus the expression nucleus of silicon will be 
Answer:
Chemical reactions often involve changes in energy due to the breaking and formation of bonds. Reactions in which energy is released are exothermic reactions, while those that take in heat energy are endothermic.
Explanation:
Hi!
The answer is breathing.
Protozoans are organisms that can multiply themselves in humans, and serious infections can develop from one organism. The most frequently transmission methods are contaminated food or fecal contact. Dog bites inoculate bacteria into deep tissue, and they also serve as a transmission method.
Breathing is not considered to be likely to transmit protozoan infection because protozoans rarely develop in the respiratory tract.
