The average mass of an atom is calculated with the formula:
average mass = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2) + ... an so on
For the boron we have two isotopes, so the formula will become:
average mass of boron = abundance of isotope (1) × mass of isotope (1) + abundance of isotope (2) × mass of isotope (2)
We plug in the values:
10.81 = 0.1980 × 10.012938 + 0.8020 × mass of isotope (2)
10.81 = 1.98 + 0.8020 × mass of isotope (2)
10.81 - 1.98 = 0.8020 × mass of isotope (2)
8.83 = 0.8020 × mass of isotope (2)
mass of isotope (2) = 8.83 / 0.8020
mass of isotope (2) = 11.009975
mass of isotope (1) = 10.012938 (given by the question)
The location of the negative charges is evenly distributed throughout the entire atom.
J. J. Tomson concluded that atoms are divisible and that the corpuscles are their building blocks.
Atoms are made up of smaller particles.
J. J. Thomson discovered the electron ( the negative charges of the atom) in 1897.
His "plum pudding" model (1904) suggested: the electrons are embedded in the positive charge and evenly distributed throughout the entire atom.
With this model, he abandoned his earlier hypothesis that the atom was composed of immaterial vortices.
Later, Rutherford demonstrate that J.J Thompson's Plum Pudding model was not accurate.
More info about Thomson’s plum pudding model: brainly.com/question/6319700
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Answer: The stage of metamorphosis this occurs is called the PUPA stage. The correct option is D.
Explanation:
Metamorphosis can be defined as the change in form, mode of life and behaviour that occurs during embryonic development of an organism. In the metamorphosis of insects, which mostly reproduce sexually, insects can be grouped according to the way the eggs develop into adults. Some show:
--> Complete metamorphosis or
--> Incomplete metamorphosis.
In the life cycle of a butterfly, a COMPLETE metamorphosis occurs. This is because after fertilization, the EGG hatches into LARVA which passes through a PUPAL stage before becoming transformed into an ADULT insect. That is:
Egg --> Larva --> Pupa --> Imago.
When the caterpillar, which is the Larva stage, has reached its full size, it spins a pad of silk on a twig. It moves upward and attached it's clasper to this pad. It spin another silk thread at the thorax. These aids it to assume a slanting position with the head end pointing upwards. The pupa stage called the CHRYSALIS is reached when it tucks it's head under its thorax, arches it's body, shortens and broadens, and moults for the last time. Therefore the correct option is D (pupa).
Answer:
Aluminium metal reacts vigorously with all the halogens to form aluminium halides. So it reacts with chlorine, bromine, and iodine.
Molarity: M = #moles of solute / liters of solution
# moles = mass / molar mass
Molar mass calculation
Barium hydroxide = Ba (OH)2
Atomic masses
Ba = 137.4 g/mol
O=16 g/mol
H=1 g/mol
Molar mass of Ba (OH)2 = 137.4 g/mol + 2*16g/mol + 2*1 g/mol = 171.4 g/mol
# mol = 25.0g/171.4 g/mol = 0.146 mol
For the volume of water use the fact that the density is 1g/ml., so 120 g = 120 ml = 0,120 liters.
M = 0.146mol / 0.120 liters = 1.22 mol/liter
