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3 years ago

All isotopes of an element with an atomic number greater than ___ are radioactive.

Chemistry

1 answer:

algol [13]3 years ago

4 0

Answer:

83 .

Explanation:

Radioactive elements: It is defined as the atoms which contains unstable nucleus because of the constantly change and imbalance of energy in the nucleus. Radioactivity of an atom is showing by when the nucleus of an atom loose a neutron, it gives an energy and this process is called to be radioactivity.

Isotopes elements containing different number of neutrons and same number of protons. All isotopes are not considered as radioisotopes. All isotopes of an element with an atomic number greater than 83 are radioactive means, they are having unstable nucleus.

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How many moles of oxygen atom are there in 0.5 moles of Ca(ClO3) 2?

FinnZ [79.3K]

Answer:

Do a quick conversion: 1 moles Ca(ClO3)2 = 206.9804 gram using the molecular weight calculator and the molar mass of Ca(ClO3)2. ... How many moles Ca(ClO3 )2 in 1 grams? ... of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together.

Explanation:

(jayaanilanmol's answer)

3 0

3 years ago

Check all that apply.

White raven [17]

Answer:

4 for C in CH4

+4 for C in CO2

-2 for O in all substances

+1 for H in both CH4 and H2O

option 1,2,3 and 4 are correct. Option 5 is not correct

Explanation:

Step 1: Data given

Oxidation number of H = +1

Oxidation number of O = -2

Step 2: The balanced equation

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

Step 3: The oxidation numbers

-4 for C in CH4

⇒ Oxidation number of H = +1

⇒ 4x +1 = +4

C has an oxidation number of -4

This is correct.

+4 for C in CO2

⇒ Oxidation number of O = -2

⇒ 2x -2 = -4

C has an oxidation number of +4

This is correct.

-2 for O in all substances

⇒ this is correct, the oxidation number of O is always -2 (except in H2O2 and Na2O2)

This is correct.

+1 for H in both CH4 and H2O

⇒ this is correct, the oxidation number of H is always +1 (except in metal hydrides).

This is correct.

+4 for O in H2O

⇒ Oxidation number of H = +1

⇒ 2x +1 = +2

The oxidation number of O is -2

This is not correct

5 0

3 years ago

a piece of metal is heated to 100℃ and placed into 75.0g of water in a coffee-cup calorimeter. Initially, the temperature of the

Jet001 [13]

Answer:

The mass of this piece of metal is 37.68g

Explanation:

<u>Step 1:</u> Given data

q = m*ΔT *Cp

⇒with m = mass of the substance

⇒with ΔT = change in temp = final temperature T2 - initial temperature T1

⇒with Cp = specific heat (Cpwater = 4.184J/g °C) (Cpmetam = 0.9J/ g °C)

For this situation : we get for q = m*ΔT *Cp

q(lost, metal) = q(gained, water)

- mass of metal(ΔT)(Cpmetal) = mass of water (ΔT) (Cpwater)

-m (30.6 -100) * 0.9 = 75g *( 30.6 - 23.1) * 4.184J / g °C

-m * (-69.4) * 0.9 = 75g * (7.5) * 4.184J / g °C

-m * (-69.4) *0.9 = 2353.5

-m = 2353.5 / (-69.4 *0.9) = -37.68

m = 37.68g

The mass of this piece of metal is 37.68g

4 0

3 years ago

When taking ph measurements of solutions, why is it important to stir thoroughly after adding each reagent?.

Anon25 [30]

Mixing helps ensure that the measured pH is reflective of the entire solution

6 0

2 years ago

Which distinguishes a dwarf planet from a planet?

Rashid [163]

Answer:

It's size

Explanation:

The definition of a dwarf planet is "a celestial body that orbits the sun and has a spherical shape but is not large enough to disturb other objects from its orbit"

Essentially, "dwarf" is an adjective. Just like saying the colour distinguishes a purple planet...

6 0

3 years ago

Read 2 more answers