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IRINA_888 [86]
3 years ago
13

When helium was discovered by humans?

Chemistry
1 answer:
saul85 [17]3 years ago
8 0
Helium was discovered in 1868.
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Which of the following is not the same as 5.63 grams?<br> 5,630 mg<br> 0.563 hg <br> 0.00563 kg
Lady bird [3.3K]
Units of measure is defined as a the magnitude of a certain quantity. There are a lot of units that we can use for mass. Kilograms, grams, tons, pounds and slugs are some of the examples. There are some units where certain prefixes changes its magnitude. One thousand grams is one kilogram. One thousand mg is one gram. 5.63 grams is 5,630 mg and 0.00563 kg is 5.63 grams. Hence the answer here is 0.563 hg. 
6 0
3 years ago
Read 2 more answers
2Al + 6HCl → 2AlCl3 + 3H2 If 3.0 grams of H2 were produced, how many grams of Al reacted? (Molar mass of Al = 27 g/mol, molar ma
Monica [59]
Hope it cleared your doubt.

8 0
3 years ago
Which sample contains the greater number of atoms, a sample of Li that contains 6.8 x 10^22 atoms or a 1.97 mole sample of Na?
IrinaVladis [17]

Answer:

                     1.97 moles of Na contains greater number of atoms than 6.8 × 10²² atoms of Li.

Explanation:

                    To solve this problem we will first calculate the number of atoms contained by 1.97 moles of Na and then will compare it with 6.8 × 10²² atoms of Li.

                    As we know that 1 mole of any substance contains exactly 6.022 × 10²³ particles which is also called as Avogadro's Number. So in order to calculate the number of atoms contained by 1.97 moles of Na, we will use following relation,

          Moles  =  Number of Atoms ÷ 6.022 × 10²³ atoms.mol⁻¹

Solving for Number of Atoms,

          Number of Atoms  =  Moles × 6.022 × 10²³ Atoms.mol⁻¹

Putting values,

          Number of Atoms  =  1.07 mol × 6.022 × 10²³ Atoms.mol⁻¹

          Number of Atoms  = 1.18 × 10²⁴ Atoms of Na

Hence,

          1.97 moles of Na contains greater number of atoms than 6.8 × 10²² atoms of Li.

4 0
3 years ago
If 27.50 mL of 0.120 M NaOH neutralizes 0.248 g of HAA, what is the molar mass of unknown amino acid
tino4ka555 [31]

Answer:

75.15 g/mol

Explanation:

First, let us look at the equation of reaction;

NaOH + HAA --> NaAA + H_2O

From the balanced equation of reaction, 1 mole of NaOH is required to completely neutralize 1 mole of HAA.

Recall that: mole = molarity x volume.

Therefore, 27.50 mL, 0.120 M NaOH = 0.0275 x 0.120 = 0.0033 moles

0.0033 mole of NaOH will therefore requires 0.0033 moles of HAA for complete neutralization.

In order to find the molar mass of the unknown amino acid, recall that:

<em>mole = mass/molar mass</em>, hence, <em>molar mass = mass/mole</em>.

Therefore, molar mass of HAA = 0.248/0.0033 = 75.15 g/mol

6 0
3 years ago
There is a part A and B
ladessa [460]

Answer:

Im so confused, and maybe blind bcs I cant read it

Explanation:

Could you explain??

3 0
3 years ago
Read 2 more answers
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