Dubnium is a synthetic element ... Number 105. It can be created
in a laboratory but it's not found in nature.
Fifteen (15) different isotopes of Dubnium have been created. They all
have 105 protons in the nucleus of every atom, but they have anywhere
from 256 to 270 neutrons in each nucleus.
The most stable isotope of Dubnium is ²⁶⁸Db , with 163 neutrons in the
nucleus. That form of Dubnium atom has a 50-50 chance of surviving
for around 28 hours before it falls apart.
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Your answer should be D
let me know if I got it wrong
Hope this helped!
The potential energy of the block is A) 490 J
Explanation:
The potential energy of an object is the energy possessed by the object due to its position in the gravitational field.
It is calculated as follows:

where
m is the mass of the object
g is the acceleration due to gravity
h is the height of the object above the ground
For the block in this problem, we have:
m = 10 kg

h = 5 m
Therefore, its potential energy is:

Learn more about potential energy:
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Water is a compound because it always has two hydrogen atoms for each oxygen atom. Water can be broken down into simpler substances. Water is a compound because pure water is composed of only H₂O molecules. Each molecule of water is a chemical combination of two hydrogen atoms and one oxygen atom. Water is a type of molecular compound.

<h3>Further explanation</h3>
- Compounds are substances composed of two or more different elements chemically combined that can be separated into simpler substances only by chemical reactions.
- Water, for example, is a compound because pure water is composed of only H₂O molecules. Each molecule of water is a chemical combination of two hydrogen atoms and one oxygen atom.
- A molecular bond or covalent bond occurs as a result of electrons can be shared between atoms. Molecular compounds have molecular (covalent) bonds.
- An ionic bond occurs as a result of electrons can be completely removed from one atom and given to another. Ionic compounds have ionic bonds.
- Examples of other molecular compounds are carbon dioxide (CO₂) and glucose (C₆H₁₂O₆). Each molecule of CO₂ is a chemical combination of two oxygen atoms and one carbon atom. Each molecule of C₆H₁₂O₆ is a chemical combination of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.
- Table salt (NaCl) is a compound because it is made from more than one kind of element (Na and Cl), but it is not a molecule because the bond that holds NaCl together is an ionic bond. An electron from the outer shell of sodium is released and taken by chlorine to reach octet conditions on both sides, that is how ionic bonds occur. Thus NaCl is an ionic compound.
- A diatomic molecule is a molecule made from two atoms of the same type. For example, oxygen gas in the atmosphere is a molecule because it contains molecular bonds. It is not a compound because it is made from atoms of only one element, i.e. oxygen. Another example is hydrogen gas, nitrogen gas, and chlorine gas.
- Elements are the simplest forms of matter and therefore cannot be broken down into simpler substances by any chemical or physical reactions. Some examples of elements include hydrogen, oxygen, carbon, sodium, iron, and sulfur. Elements can combine with other elements to synthesize compounds.
<h3>
Learn more</h3>
- Which statement best explains water’s ability to dissolve covalent compounds? brainly.com/question/8223274
- How do ionic bonds differ from covalent bonds? brainly.com/question/2092388
- Which elements can react to produce a molecular compound? brainly.com/question/867874
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