Answer:
3 refers to the fact that three whole NH4 molecules are present. 4 refers to the fact that there are 4 hydrogen atoms in one NH4 molecule.
Explanation:
A number that comes before a molecule such as 5H2O or 6NaCl refers to how many of that molecule there are. A subscript added to an element in a molecule refers to how many atoms of that element are in the molecule.
The red-legged frog breeds in ephemeral ponds from January through March. Its relative, the bullfrog, breeds in permanent ponds from late March through May. There are two pre-mating isolation mechanism at play here,
1. Ecological isolation: The habitats are different, hence the individuals of both the species do not meet. Ephemeral ponds are temporary ponds that develop during rainy days, while the permanent ponds are full of water throughout the year.
2. Temporal isolation: The time of mating is different for both the species to avoid contact between the individuals of closely related species. Red-legged frogs mate in January to March slot and the bullfrog in the March to May slot.
Answer:
Because a 5 year old child can't take care of himself or herself. So, a 5 year old child needs more energy to fight with disease than a teenager. A teenager can take care of himself or herself to prevent him or her suffer from disease. Hence, small child needs more energy
Hope it helps
Bones are the structure of the body, muscles allow the bones to move, nerves allow messages to be sent back and forth from the brain to the mucells telling them to move, joints join the bones of your body and allow them to move.