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3 years ago

4. The elements calcium and strontium have similar chemical properties because they both have the same

Chemistry

2 answers:

Zarrin [17]3 years ago

6 0

Answer:

Answer c

Explanation:

The similar properties between calcium, strontium and potassium are : All of them have two electrons in the outermost shell. All are metals. Their oxides are alkaline.

mestny [16]3 years ago

4 0

The answer is C Becuase all of them have have two electrons in the outermost shells which is metal .

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Which observation provided Albert Einstein the clue that he needed to explain the photoelectric effect? Light is made up of extr

Aliun [14]

The correct answer is

Energy of electrons depends on light’s frequency, not intensity.

As per photoelectric effect, if we incident a light on metal surface it will results into emission of electron from it

if we increase the number of photons the number of electrons will increase however if we increase the frequency the number of photons will not increase

While if we increase frequency the energy of electrons will increase as

Energy of photon = Work function of metal + kinetic energy of electrons

7 0

3 years ago

Read 2 more answers

Dissolution of KOH, ΔHsoln:

swat32

Using Hess's law we found:

1) By adding reaction 10.2 with the reverse of reaction 10.1 we get reaction 10.3:

KOH(aq) + HCl(aq) → H₂O(l) + KCl(aq) ΔH (10.3)

2) The ΔHsoln must be subtracted from ΔHneut to get the total change in enthalpy (ΔH).

The reactions of dissolution (10.1) and neutralization (10.2) are:

KOH(s) → KOH(aq) ΔHsoln (10.1)

KOH(s) + HCl(aq) → H₂O(l) + KCl(aq) ΔHneut (10.2)

1) According to Hess's law, the total change in enthalpy of a reaction resulting from differents changes in various reactions can be calculated as the sum of all the enthalpies of all those reactions.

Hence, to get reaction 10.3:

KOH(aq) + HCl(aq) → H₂O(l) + KCl(aq) (10.3)

We need to add reaction 10.2 to the reverse of reaction 10.1

KOH(s) + HCl(aq) + KOH(aq) → H₂O(l) + KCl(aq) + KOH(s)

Canceling the KOH(s) from both sides, we get reaction 10.3:

KOH(aq) + HCl(aq) → H₂O(l) + KCl(aq) (10.3)

2) The change in enthalpy for reaction 10.3 can be calculated as the sum of the enthalpies ΔHsoln and ΔHneut:

$\Delta H = \Delta H_{soln} + \Delta H_{neut}$

The enthalpy of reaction 10.1 (ΔHsoln) changed its sign when we reversed reaction 10.1, so:

$\Delta H = \Delta H_{neut} - \Delta H_{soln}$

Therefore, the ΔHsoln must be subtracted from ΔHneut to get the total change in enthalpy ΔH.

Learn more here:

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I hope it helps you!

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3 years ago

According to VSEPR theory , in which fashion will the bonds and lone pairs of electrons be arranged about the central atom in th

Elina [12.6K]

Answer:

Tetrahedral, trigonal pyramidal, trigonal bipyramidal.

Explanation:

The VSPER theory states that the bonds of sharing electrons and the lone pairs of electrons will repulse as much as possible. So, by the repulsion, the molecule will have some shape.

In the ion PO₄³⁻, the central atom P has 5 electrons in its valence shell, so it needs 3 electrons to be stable. Oxygen has 6 electrons at the valence shell and needs 2 to be stable. 3 oxygens share 1 pair of electrons with P, and the two lone pair remaining in P is shared with the other O, then the central atom makes 4 bonds and has no lone pairs, the shape is tetrahedral.

In the ion H₃O⁺, the central atom O has 6 electrons in its valence shell and needs 2 electrons to be stable. The hydrogen has 1 electron, and need 1 more to be stable. The hydrogens share 1 pair of electrons with the oxygen, then it remains 3 electrons at the central atom, and the VSPER theory states that the shape will be a trigonal pyramidal.

In the AsF₅, the central atom As has 5 valence electrons, and F has 1 electron in its valence shell, so each F shares one pair of electrons with As, and there are no lone pairs in the central atom. For 5 bonds without lone pairs, the shape is trigonal bipyramidal.

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3 years ago

What can liquids and gases do that solids cannot?

Aleks [24]

Answer:

What can liquids do that solids cannot?Liquids will flow and fill up any shape of container. Solids like to hold their shape. In the same way that a large solid holds its shape, the atoms inside of a solid are not allowed to move around too much. Atoms and molecules in liquids and gases are bouncing and floating around, free to move where they want.

What can gases do that solids cannot?The atoms and molecules in gases are much more spread out than in solids or liquids. They vibrate and move freely at high speeds. A gas will fill any container, but if the container is not sealed, the gas will escape. Gas can be compressed much more easily than a liquid or solid.

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2 years ago

Which one of these statements best describes what a scientist is

son4ous [18]

Which of what statements

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