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27 days ago

Which of the following does not describe elements?

2 answers:

6 0

The assertion that elements can be separated through a chemical reaction is incorrect; elements are pure substances that cannot be broken down into other substances that compose them. They serve as fundamental units made of atoms.

lions [2.6K]27 days ago

3 0

Correct choice: Option (b).

Clarification:

Elements are identified as substances consisting of identical types of atoms.

No element can be split into simpler substances via physical or chemical methods.

For instance, a piece of aluminum comprises solely aluminum atoms.

The periodic table lists all natural elements.

Hence, it can be concluded that among the options given, the claim that elements can be separated by a chemical reaction is inaccurate.

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What is the kinetic energy acquired by the electron in hydrogen atom, if it absorbs a light radiation of energy 1.08x101 J. (A)

eduard [2509]

Explanation:

The following data has been provided:

Energy of radiation absorbed by the electron in the hydrogen atom = $1.08 \times 10^{-17} J$

As energy is absorbed in the form of a photon, the frequency is calculated accordingly:

E = $h \nu$

$1.08 \times 10^{-17} J$ = $6.626 \times 10^{-34} Js \times \nu$

$\nu$ = $0.163 \times 10^{17} s^{-1}$

or, $\nu$ = $1.63 \times 10^{16} s^{-1}$

It is known that $\nu = \frac{c}{\lambda}$

$1.63 \times 10^{16} s^{-1} = \frac{3 \times 10^{8} m/s}{\lambda}$

$\lambda$ = $1.84 \times 10^{-8} m$

According to the De-Broglie equation $\lambda = \frac{h}{p}$

with p = $m \times \nu$

So, $\lambda = \frac{h}{m \times \nu}$

$m \times \nu = \frac{6.626 \times 10^{-34} Js}{1.84 \times 10^{-8} m}$ = $3.6 \times 10^{-26} J/m$

Squaring both sides gives us:

$(m \times \nu)^{2}$ = $(3.6 \times 10^{-26} J/m)^{2}$

$12.96 \times 10^{-52}$ = $m \times \nu^{2} = \frac{12.96 \times 10^{-52}}{m}$

where m = mass of the electron

Therefore, $m \times \nu^{2} = \frac{12.96 \times 10^{-52}}{m}$

= $\frac{12.96 \times 10^{-52}}{9.1 \times 10^{-31}}$

= $1.42 \times 10^{-21}$ J

Since K.E = $\frac{1}{2}m \nu^{2}$

= $\frac{1.42 \times 10^{-21} J}{2}$

= $0.71 \times 10^{-21} J$

Our conclusion is that the kinetic energy gained by the electron in the hydrogen atom is $7.1 \times 10^{-22} J$ .

4 0

25 days ago

Which of the following reactions is a redox reaction? (a) K2CrO4 + BaCl2 → BaCrO4 + 2KCl (b) Pb2+ + 2Br- → PbBr2 (c) Cu + S → Cu

castortr0y [2731]

Explanation:

The following reactions are presented:

(a) K₂CrO₄ + BaCl₂ → BaCrO₄ + 2 KCl

(b) Pb²⁺ + 2 Br⁻ → PbBr₂

Reaction (c) represents a redox reaction, as the oxidation states of the elements are changing. In this case:

Cu + S → CuS

In its elemental form, Cu has an oxidation state of 0, while in CuS (copper sulfide), its oxidation state changes to +2.

Similarly, S in its elemental form has an oxidation state of 0 and is -2 in CuS (copper sulfide).

Learn more about:

redox reactions

7 0

1 month ago

13.3 g of benzene (C6H6) is dissolved in 282 g of carbon tetrachloride. What is the molal concentration of benzene in this solut

Tems11 [2390]

Answer:

0.605 molal

Explanation:

Molality indicates the solute amount in a specific solvent mass.

Let’s find the amount of benzene solute.

Mass of benzene = 13.3g

Molar mass of C6H6 = 12*6 +1*6 =72+7=78g/mol

Amount of benzene = mass/molar mass

=13.3/78

=0.1705mol

Molality = amount of solute/mass of solvent in kg

Mass of solvent = 282g = 0.282kg

Molality = 0.1705/0.282

=0.605 molal

6 0

11 days ago

Put the list in chronological order (1–5).

alisha [2704]

Explanation:

Filtration serves as a method of separation where solid particles that are suspended in a liquid are isolated by passing the mixture through filter paper's pores. This process ensures that the solid particles accumulate on the filter paper and the liquid flows out through the filter paper's pores.

The ordered sequence of the steps provided is:

Measure and fold the filter paper.
Insert the filter paper into the funnel, then position the funnel above the Erlenmeyer flask.
Let the solid/liquid mixture pass through the filter.
Rinse the filter paper that holds the mixture with water.
Measure the weight of the dry filter paper along with the copper.

4 0

27 days ago

Read 2 more answers

Examine the sets of bonds given in the choices. which one arranges the bonds in order of increasing (shortest to longest) bond l

Tems11 [2390]

The stronger the attraction between elements, the shorter the bond length becomes; conversely, a weaker attraction results in a longer bond length. This attraction arises from differences in their electronegativities, which is the capacity of an element to draw electrons toward itself. According to periodic trends, electronegativity rises as you move left to right and bottom to top on the periodic table. Therefore, the order from the most electronegative to the least is: Cl > Br > I. As a result, the sequence by bond length from shortest to longest is: C-Cl > C-Br > C-I.

8 0

21 day ago