Answer:
D or A
<em>But I do know...</em>
It's because new strains of the virus are constantly appearing and evolving, so the vaccine must change along with them.
Moles (mol) = mass (g) / molar mass (g/mol)
Mass of NaCl = 21.7 g
Molar mass of NaCl = <span>58.4 g/mol
Hence, moles of NaCl = </span>21.7 g / 58.4 g/mol = 0.372 mol
Hence moles of NaCl in the mixture is 0.372 mol.
Let's assume that mixture has only given compounds and free of impurities.
Then, we can present this as a mole percentage.
mole % = (moles of desired substance / Total moles of the mixture) x 100%
Hence,
mole % of NaCl = (moles of NaCl / Total moles of the mixture) x 100%
Total moles of mixture = moles of NaCl + KCl + LiCl
Mass of KCl = 3.74 g
Molar mass of NaCl = 74.6 g/mol
Hence, moles of NaCl = 3.74 g / 74.6 g/mol = 0.050 mol
Mass of NaCl = <span>9.76 g
</span>Molar mass of NaCl = 42.4 g/mol
Hence, moles of NaCl = 9.76 g / 42.4 g/mol = 0.230 mol
Total moles = 0.372 mol + 0.050 mol + 0.230 mol = 0.652 mol
mole % of NaCl = (moles of NaCl / Total moles of the mixture) x 100%
= (0.372 mol / 0.652 mol) x 100%
= 57.06%
Hence, mixture has 57.06% of NaCl as the mole percentage.
Answer:
The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs
Explanation:
Bases have a slippery feel when touched but acids do not have a slippery feel.
- An acid is a substance that interacts with water to produce excess hydroxonium ions, H₃O⁺ in an aqueous solution. Here are some of its properties:
- Their dilute solutions have a sour taste.
- They have a burning effect on the skin and are highly corrosive on metals.
- They have the ability to change the colors of indicators.
- They react with bases to form salt and water only.
Examples of acids are:
Hydrochloric acid HCl
Tetraoxosulphate (VI ) acid H₂SO₄
- A base is a substance that interacts with water to produce excess hydroxide ions, OH⁻ in an aqueous solution.
- They typically have a bitter taste.
- They have a soapy feel
- They are electrolytes
- They also change the color of indicators
Examples are:
Potassium hydroxide KOH
Sodium hydroxide NaOH
Learn more:
Neutralization brainly.com/question/6447527
#learnwithBrainly
The rate of reaction that can be measured in the dark by determining the amount of oxygen gas consumed in a period of time is the rate of respiration.
Why?
Plants can undergo two types of reactions involving oxygen:
- <u>Photosynthesis: </u>In this type of reaction, plants use energy from light to synthesize glucose. The chemical reaction for photosynthesis is: 6H₂O + 6CO₂ → C₆H₁₂O₆ + 6O₂, and this reaction produces oxygen gas in the presence of light, that means that to measure the rate of photsynthesis, you'll need to measure the amount of oxgen gas <u>produced</u> in a period of time.
- <u>Respiration:</u> In this type of reaction, plants convert the energy stored in the chemical bonds of molecules such as glucose to obtain energy. The chemical reaction for respiration is: C₆H₁₂O + 6O₂ → 6H₂O + 6CO₂, since this reaction consumes oxygen gas in the dark, that means that to measure the rate of respiration, you'll need to measure the amount of oxygen gas <u>consumed</u> in a period of time.
Have a nice day!
