In order for an atom to be neutral (i.e. have no charge), it must have the same number of ______ as it has protons. a. neutrons
1 answer:
Answer : The correct option is, (b) There is a same number of electrons.
Explanation :
For the neutral atom, the number of protons and electrons are equal. But, they are unequal when the atoms present in the form of ions or the atom has some charges.
When an unequal number of electrons and protons then it leads to the formation of ionic species.
Ion : An ion is formed when an atom looses or gains electron.
When an atom looses electrons, it will form a positive ion known as cation.
When an atom gains electrons, it will form a negative ion known as anion.
For example : The neutral atom Mg has equal number of protons and electrons i.e 12 but ion has unequal number of protons and electrons that means it has 12 number of protons and 10 number of electrons.
Hence, the correct option is, (B) electrons
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Answer:
0.4 g of hydrogen gas would be produced.
1. 0.48 mole of HCl is needed to react completely with 15.5 g of zinc.
2. HCl is the limiting reactant.
3. 2.61 g of zinc is in excess
Explanation:
From the balanced equation of reaction:
1 mole of Zn requires 2 moles of HCl to produce 1 mole of hydrogen gas.
15.5 g of zinc = 15.5/65.3 = 0.24 moles of zinc.
0.24 moles Zn is supposed to require 0.24 x 2 moles HCl which is equivalent to 0.48 moles HCl.
But only 0.400 mole of HCl is present. <u>Hence, HCl is the limiting reagent</u>. <u>For complete reaction with 15.5 g of Zinc, 0.48 mole HCl would be needed.</u>
0.400 mole of HCl will require 0.2 mole of Zn for complete reaction. <u>This thus means that 0.24 - 02 = 0.04 mole of Zn is in excess.</u>
0.04 mole Zn = 0.04 x 65.3 = 2.61 g excess Zn.
Now, since HCl is the limiting reagent;
2 moles of HCl is required to produce 1 mole of H2 according to the equation.
0.400 mole HCl will therefore yield 0.400 x 1/2 = 0.2 mole H2
0.2 mole H2 = 2 x 0.2 = 0.4 g H2
<em>Hence, </em><em>0.4 g</em><em> of hydrogen gas would be produced.</em>
To answer this question, you need to know the concept of half-life, which is how a radioactive material decreases in mass over time.
The half life of U-235 is 703.8 million years. The first part of this problem is to find the scale factor. To do this, divide the time that has past by the half life, like this:
Now, take this scale factor and multiply it by the current mass, like this:
This number is what you add to the current mass to get the original mass. That is because the scale factor showed us that it was just over one half life. Since after one half life, the mass is cut in half, and this is over one half life, when we add to the original it will be a little over double. This equation illustrates the final addition:
I hope this helped you. Fell free to ask any further questions.
The half life of U-235 is 703.8 million years. The first part of this problem is to find the scale factor. To do this, divide the time that has past by the half life, like this:
Now, take this scale factor and multiply it by the current mass, like this:
This number is what you add to the current mass to get the original mass. That is because the scale factor showed us that it was just over one half life. Since after one half life, the mass is cut in half, and this is over one half life, when we add to the original it will be a little over double. This equation illustrates the final addition:
I hope this helped you. Fell free to ask any further questions.