I think it might be Selenium.
Explanation:
To round to a significant figure:
- look at the first non-zero digit if rounding to one significant figure
- look at the digit after the first non-zero digit if rounding to two significant figures
- draw a vertical line after the place value digit that is required
- look at the next digit
- if it's 5 or more, increase the previous digit by one
- if it's 4 or less, keep the previous digit the same
- fill any spaces to the right of the line with zeros, stopping at the decimal point if there is one
<h3>
<em>Hope</em><em> </em><em>it</em><em> </em><em>will</em><em> </em><em>help</em><em> </em><em>you</em><em>.</em><em>.</em><em>.</em><em>.</em><em>.</em></h3>
Answer:
The third option "A molecule of a compound is composed of at least two types of atoms" is correct
Explanation:
This question isn't about molecules, it's about elements and compounds.
Elements are made of one and only one type of atoms, while compounds are made of more than one type of atoms.
(Molecules are just groups of atoms, it doesn't matter what they're made of)
I would say 6.022<span>⋅1023 atom</span>
Answer:
17.86mL of the HCl solution
Explanation:
The reaction of CaCO₃ with HCl is:
CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O
The concentration of HCl with a pH of 1.52 is:
pH = 1.52 = -log [H⁺]
[H⁺] = 0.0302M = [HCl]
27.0mg = 0.0270g of CaCO₃ (Molar mass: 100.09g/mol) are:
0.0270g of CaCO₃ ₓ (1mol / 100.09g) = <em>2.70x10⁻⁴ moles of CaCO₃</em>
Moles of HCl to react completely with these moles of CaCO₃ are:
2.70x10⁻⁴ moles of CaCO₃ ₓ (2 mol HCl / 1 mol CaCO₃) =
5.40x10⁻⁴ moles of HCl
As the concentration of HCl is 0.0302M, volume in 5.40x10⁻⁴ moles is:
5.40x10⁻⁴ moles of HCl * (1L / 0.0302mol) = 0.01786L =
<h3>17.86mL of the HCl solution</h3>
