They have short wings enabling them to fly with a lot of speed and
maneuverability
Answer: By definition, if the atomic number =
7
, then there are 7 protons, 7 electrons, and 8 neutrons!
Explanation:
The atomic number is by definition the number of protons, positively charged particles, contained within the atomic nucleus. So if there are 7 protons, there MUST be 7 electrons, 7 negatively charged particles. Why? Because matter is electrically neutral, and positive and negative particles must be equal.
Electrons have negligible mass; the mass number depends on the number of protons contained within the nucleus, PLUS the number of neutrons. Given that we have 15 N
, there must be 8 neutrons contained within the nucleus. does this help?
Answer:
The density of the liquid is 0.87 g/ml
Explanation:
Density = 17.4g divides 20ml = 0.87 g/ml (rounded to one significant figure)
Answer:
The correct option is <em>B. 0.1 </em>
Explanation:
According to the information provided in the question, a zebra eats 10 kg of grass. This zebra is then eaten up by a lion.
Researched have shown that approximately 10% of an energy transfer is made from one trophic level to another. The rest of the energy is lost.
Hence, 10 kg of grass will give :
10/100× 10
= 1% or 1 kg of energy to the zebra
The grass will give
1/100× 10
= 0.1% or 0.1 kg of energy to the lion.
The difference between an artery and a vein is that arteries are larger, more muscular and more elastic than veins; they carry blood that is under pressure from having been pumped out of the heart; veins are under much less pressure, so they are not as strong
