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sveticcg [70]
3 years ago
6

.org Questions What are some of the uses for gold described in the passage?

Chemistry
1 answer:
lesya692 [45]3 years ago
4 0
What’s the passage??
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Which bonds are found inside a water molecule, between hydrogen and oxygen?
Papessa [141]
Hydrogen bond is found between water molecule if im correct
5 0
3 years ago
Which statements accurately describe Dmitri Mendeleev’s contributions to the development of the periodic table? Check all that a
Varvara68 [4.7K]

Answer:

  • <em><u>Mendeleev produced the first orderly arrangement of known elements.</u></em>

  • <em><u>Mendeleev used patterns to predict undiscovered elements.</u></em>

Explanation:

  • <u>Mendeleev produced the first orderly arrangement of known elements and used patterns to predict the undiscovered elements.</u>

        Those two statments are true.

For the time being there were some 62 known elements. Before Medeleev some schemes to order part of the elements were proposed, but Medeleev showed the relationship between the atomic mass and the properties of the elements (supports second choice). This arrangement is known as the periodic table.

More importantly, Mendeleev predicted correctly the existance and properties of unknown elements, which is his major contribution: he left blanket spaces which where gradually filled when new elements where discovered (this supports the fourth choice).

The first modern chemistry book was written by Antoine Lavoisier (this discards first option).

Mendeleev ordered the elements by increasing mass number (this discards third choice), which was corrected later by the scientist Henry Moseley, who ordered the elements by increasing atomic number (number of protons).

Isotopes were not known by Mendeleev times, so this discards the last option.

8 0
3 years ago
Read 2 more answers
The labels have fallen off three bottles containing powdered samples of metals; one contains zinc, one lead, and the other plati
Alinara [238K]

Here we have to identify the metal powder by the given disposal.

The identification of Zinc can be done by 1 m nitric acid (HNO₃) and Ni(NO₃)₂ which will produce hydrogen gas by reaction and displacement reaction as shown below.

Zn + 2 HNO₃ = Zn(NO₃)₂ + H₂ (g)

Zn + Ni(NO₃)₂ = Zn(NO₃)₂ + Ni

The identification of lead can be done by the reaction with 1 m nitric acid (HNO₃) which produces lead nitrate.

The reaction is-

Pb + 4HNO₃ = Pb(NO₃)₂ + 2NO₂ + 2H₂O

The identification of platinum can be done by the reaction with all the given disposal as it will not react with any of the compound.

1. Identification of Zinc (Zn):

(a) Zn metal will not react with sodium nitrate (NaNO₃) as sodium remains at the lower position of the activity series than zinc.

Zn + NaNO₃ = No reaction

(b) Zn metal will react with 1 m HNO₃ to form hydrogen gas. The reaction is:

Zn + 2 HNO₃ = Zn(NO₃)₂ + H₂ (g)

(c) Zn will react with nickel nitrate [Ni(NO₃)₂] because it may only cause displacement reaction the reduction potential of Zn²⁺/Zn (-0.76) is less than that of Ni²⁺/Ni (-0.23). Thus the reaction will be:

Zn + Ni(NO₃)₂ = Zn(NO₃)₂ + Ni

2. Identification of lead (Pb):

(a) Pb metal will not react with sodium nitrate (NaNO₃) as sodium remains at the lower position of the activity series than Pb.

Pb + NaNO₃ = No reaction

(b) Pb reacts with HNO₃ to form lead nitrate. The reaction is:

Pb + 4HNO₃ = Pb(NO₃)₂ + 2NO₂ + 2H₂O

(c) The standard reduction potential of Pb²⁺/Pb is more than nickel Ni²⁺/Ni thus there will be no reaction between Pb and NI(NO₃)₂.

Pb + Ni(NO₃)₂ = No reaction.

3. Identification of platinum (Pt)

(a) Pt metal will not react with sodium nitrate (NaNO₃) as sodium remains at the lower position of the activity series than Pt.

Pt + NaNO₃ = No reaction.

(b) The standard reduction potential of Pt²⁺/Pt is so high (+1.188) thus there will be no reaction with HNO₃.

Pt + HNO₃ = No reaction

(c) The standard reduction potential of Pt²⁺/Pt is more than nickel Ni²⁺/Ni thus there will be no reaction between Pt and Ni(NO₃)₂.

Pt +  Ni(NO₃)₂ = No reaction.    

8 0
3 years ago
PLEASE ANSWER
Vikki [24]
D) refracted
because , the light changes direction.. causing the penny to look bigger than it is.
4 0
3 years ago
The Resource Conservation and Recovery Act controls hazardous waste from its creation to its disposal. Please select the best an
o-na [289]

Answer:

True

Explanation:

Resource Conservation and Recovery Act (RCRA). 1976 of United States Environmental Protection Agency(EPA) empowers EPA to control the production, transportation, storage, treatment and disposal of hazardous waste. The RCRA act was amended in 1984 and 1986 to include Waste minimization along with appropriate disposal (not in the landfill site) and tackling of petroleum hazardous waste respectively along with other waste.

7 0
3 years ago
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