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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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If a molecule has an empirical formula of C2H2O and a molecular mass of 84.0 g/mol, what is the molecular formula?
lord [1]

Answer:

=C₄H₄O₂

Explanation:

Given the empirical formula of a molecule, the he the quotient of the molecular mas and and the empirical mass=constant.

84.0 g/mol/mass of(C₂H₂O)=constant

=84/(12×2+1×2×16)

=84/42

=2

Therefore, the molecular formula is (C₂H₂O)₂=C₄H₄O₂

6 0
3 years ago
Read 2 more answers
Which best describes the relative positions of protons, neutrons, and electrons in an atom?
Anastaziya [24]
Hello!

The center of an atom is called the nucleus; it is comprised of protons and neutrons, collectively known as nucleons. The electrons float around the nucleus in a cloud.

Answer:
A) Protons and neutrons are in the center of the atom, and electrons move around in the cloud.
6 0
3 years ago
In the partition coefficient experiment 4A this week, after thorough mixing of the reagents, phase separation will occur. The to
Andreas93 [3]

Answer:

The top layer is the Aqueous layer, and the benzoic acid is contained in the non-aqueous layer/oil phase.

Explanation:

A separating funnel is a very important piece of laboratory glassware that is used to separate the components of liquid-liquid mixtures  which are immiscible. This technique is used in the extraction of the components of mixtures.

The liquids separate into two phases. The separation is based on the differences in the liquids' densities, where the denser liquid settles below and the lower density liquid stays afloat. Liquids used for this kind of separation are usually different liquids, one is the aqueous layer and the other, a non-aqueous layer.

Partition coefficient or distribution coefficient is defined as the ratio of the concentrations of a compound in two immiscible solvents at equilibrium.

Organic solvents (except halogenated organic compounds) with densities greater than that of water i.e 1g/mL ( usually called the oil phase) settle at the bottom of the aqueous phase.

Benzoic acid. will settle at the bottom layer ( i.e the lower phase).

7 0
3 years ago
How is the oxidation state of a transition metal determined from the chemical formula ?
Vera_Pavlovna [14]

Answer:

Explanation:

In a chemical formula, the oxidation state of transition metals can be determined by establishing the relationships between the electrons gained and that which is lost by an atom.

We know that for compounds to be formed, atoms would either lose, gain or share electrons between one another.

The oxidation state is usually expressed using the oxidation number and it is a formal charge assigned to an atom which is present in a molecule or ion.

To ascertain the oxidation state, we have to comply with some rules:

  • The algebraic sum of all oxidation numbers of an atom in a neutral compound is zero.
  • The algebraic sum of all the oxidation numbers of all atoms in an ion containing more than one kind of atom is equal to  the charge on the ion.

For example, let us find the oxidation state of Cr in Cr₂O₇²⁻

This would be:  2x + 7(-2) = -2

                          x = +6

We see that the oxidation number of Cr, a transition metal in the given ion is +6.

7 0
3 years ago
Read 2 more answers
Which is the empirical formula for a compound that contains 64.75g nitrogen and 185.25 oxygen
Svetach [21]

Answer:

What is the formula for a compound that contains 64.75 g nitrogen and 185.25 g oxygen? D. N2O5

The name of a hydrate is calcium chloride dihydrate. What is its formula? B. CaCl2 x 2H20

Explanation:

BRAINLIEST PLZZZZ

5 0
3 years ago
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