B. 39 protons, 30 neutrons, 30 neutrons
C. 39 protons, 30 neutrons, 39 electrons
D. 30 protons, 39, neutrons, 30 electrons
Answer:
D. 30 protons, 39 neutrons, 30 electrons
Explanation:
The atomic number (Z) is the number of protons (p) in the nucleus. Since
Z = 30, p = 30.
In a neutral atom, the number of electrons (e) equals the number of protons. Since p = 30, e = 30.
The mass number (A) is the number of protons plus the number of neutrons (n).
A = p + n
For an atom of zinc-69,
69 = 30 + n Subtract 30 from each side and transpose
n = 39
Zinc has the chemical symbol Zn and the atomic number 30. D. 30 protons, 39, neutrons, 30 electrons
Zinc has the chemical symbol Zn, and its atomic number is 30. This means that every atom of zinc contains 30 protons in its nucleus.
An atom of zinc-69 (Zn-69) is one that contains:
- 30 protons (since zinc has an atomic number of 30).
- 39 neutrons (subtract the atomic number from the mass number: 69 - 30 = 39).
- 30 electrons (in a neutral atom, the number of electrons is equal to the number of protons).
So, the correct option is option d 30 protons, 39 neutrons, 30 electrons.
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Answer:
Susana's red crystal sample is a compound because it was broken down into a gas and blue powder. It is not an element because elements cannot be broken down into simpler substances by ordinary means, such as heating.
Explanation:
The red crystals heated by Susana are a compound because they released a gas and turned into a blue powder when heated, indicating a chemical change.
The sample of red crystals that Susana heated up is a compound, not an element. We can come to this conclusion because when the sample was heated, a gas was released and a different substance, a blue powder, was left behind.
This indicates a chemical change had occurred, where the original substance decomposed into different substances. Compounds are known to break down into simpler substances or elements under certain conditions.
An example similar to this would be when blue copper sulfate loses water and becomes white upon heating, or when mercury(II) oxide is heated and decomposes into mercury and oxygen.
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(2) 2H2 + O2 --> 2H2O
(3) H2SO4 + Mg --> H2 + MgSO4
(4) HCl + KOH --> KCl + H2O
The gravitational potential energy not only depends on the mass of the substance but also on the height it positioned. Hence, two objects with same mass does not have same potential energy if they are not in same height.
Gravitational potential energy of an object is the energy generated by virtue of its position in gravitational field. Gravitational force is exerted by one object by which it attracts other objects into its centre of mass.
The gravitational force is dependant upon the mass of the object as well to the distance between the objects. Similarly the potential energy p is proportional to the mass m, gravity g and the height from the surface h.
Hence p = mgh.
As per this relation potential energy is not only affected by the mass but also the height at which the objects are located.
If an object is placed at a height higher than other object having same mass then it stores greater potential energy. Hence, we can't agree with the statement .
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Answer:
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