Answer:
B
Explanation:
Chemistry is the study of matter, its composition and the changes it undergoes.
Answer:
he distance to a star can be found by comparing its luminosity to its apparent brightness.
Explanation: A star that is far away will be very dim compared to its luminosity. So it proves that the ratio of its luminosity to apparent brightness will be greater than for a nearby star.
Answer:
Explanation:
Ions:
When an atom lose or gain electron ions are formed.
There are two types of ions anion and cation.
Anion:
When an atom gain electron negative charge is created and anion is formed.
X + e⁻ → X⁻
Cation:
When an atom lose electron positive charge is created and cation is formed.
X → X⁺ + e⁻
Electron:
The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.
Symbol= e-
Mass= 9.10938356×10-31 Kg
It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.
He constructed the glass tube and create vacuum in it. He applied electric current between electrodes. He noticed that a ray of particles coming from cathode to wards positively charged anode. This ray was cathode ray.
Properties of cathode ray:
The ray is travel in straight line.
The cathode ray is independent of composition of cathode.
When electric field is applied cathode ray is deflected towards the positively charged plate.
Hence it was consist of negatively charged particles.
Neutron and proton:
While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.
Symbol of proton= P+
Symbol of neutron= n0
Mass of proton=1.672623×10-27 Kg
Mass of neutron=1.674929×10-27 Kg
Answer:
C.Echinoderms have radial symmetry and worms have bilateral symmetry
Explanation:
Echinoderms evolved from animals with bilateral symmetry. The larvae of all echinoderms are bilaterally symmetrical but lost during metamorphosis developing into radial symmetry adult. Examples of echinoderms are starfish, sea urchins, sand dollars.
Worms are invertebrate animals having bilateral symmetry. They have a definite anterior (head) end and a posterior (tail) end. Worms have brains that help them detect objects, food, mates, and predators quickly.
