Answer is 56 protons and 56 electrons.
<em>Explanation;</em>
Atomic number is equal to number of protons. Hence, when the atomic number is 56, it means that atom has 56 protons.
When the element is in neutral state, number of protons = number of electrons. Hence, we can say that barium atom has 56 electrons.
But same element can have different number of neutrons. Those are called isotopes. Hence, we cannot say that there are 56 neutrons in barium atom without having its mass number. (Mass number = number of protons + number of neutrons)
Answer: D) 1.00 g
Explanation:
According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at same pressure and temperature. That means,
or,
where,
= initial volume of gas = 2.00 L
= final volume of gas = 3.00 L
= initial moles of gas =
= final moles of gas = ?
Now we put all the given values in this formula, we get
Mass of helium =
Thus mass of helium added = (3.00-2.00) g = 1.00 g
<h3>
Answer:</h3>
H+ contains 1 proton, 0 neutrons, 0 electrons.
<h3>
Explanation:</h3>
- An atom is the smallest particle of an element that can take part in a chemical reaction.
- Atoms are made of sub-atomic particles neutrons and protons found in the nucleus and electrons found in the energy levels.
- A hydrogen atom contains 1 proton and 0 neutrons in the nucleus and 1 electron in the energy levels.
- A hydrogen atom loses an electron to form an ion with 1 proton, 0 neutron and 0 electron.
Answer:
To prepare 1.00 L of 2.0 M urea solution, we need to dissolve 120 g of urea in enough water to produce a total of 1.00 L solution
Explanation:
Molarity of a solute in a solution denotes number of moles of solute dissolved in 1 L of solution.
So, moles of urea in 1.00 L of a 2.0 M urea solution = 2 moles
We know, number of moles of a compound is the ratio of mass to molar mass of that compound.
So, mass of 2 moles of urea = 
Therefore to prepare 1.00 L of 2.0 M urea solution, we need to dissolve 120 g of urea in enough water to produce a total of 1.00 L solution
So, option (C) is correct.
The density of magnesium will be 1.74 g/cm³ if 23.5 g of magnesium occupies 13.5 cm³
<h3>What is Density ?</h3>
Density is the measurement of how tightly a material is packed together.
It is defined as the mass per unit volume.
Given ;
- Mass = 23.5 g
- Volume = 13.5 cm³
Formula to calculate density ;
Density = mass / volume
=23.5 / 13.5 = 1.74 g/cm³
Hence, the density of magnesium will be 1.74 g/cm³ if 23.5 g of magnesium occupies 13.5 cm³.
Learn more about density here ;
brainly.com/question/15164682
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