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docker41 [41]
3 years ago
10

A) 3 and 4 b) 2 and 3 c) 1 and 2 d) 1 and 4

Chemistry
1 answer:
tatiyna3 years ago
4 0
<h3>Answer:</h3>

d) 1 and 4

<h3>Explanation:</h3>
  • Elements are made up of particles known as atoms.
  • Atoms of the same element have the same properties as the element.
  • The atoms of an element may differ in terms of the number of neutrons and have a different mass number, such atoms are known as isotopes.
  • However, the isotopes have an equal number of protons or atomic number.
  • In this case, atom 1 has a mass number of 20 and an atomic number of 10 while atom 4 has a mass number of 21 and an atomic number of 21.
  • Therefore, atom 1 and 4 are isotopes of element E.

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At a certain temperature the rate of this reaction is first order in SO₃ with a rate constant of 0.208 s⁻¹:
NNADVOKAT [17]

Answer:

0.30 M

Explanation:

Using integrated rate law for first order kinetics as:

[A_t]=[A_0]e^{-kt}

Where,  

[A_t] is the concentration at time t  = ?

[A_0] is the initial concentration  = 1.36 M

k is the rate constant = 0.208 s⁻¹

t = 7.30 seconds

So,  

[A_t]=1.36\times e^{-0.208\times 7.30}\ M=0.30\ M

8 0
3 years ago
How do I answer and do this
Alecsey [184]

a) When the reaction takes place a yellow precipitate will be formed.

b) The law of conservation of mass is true.

<u>Explanation:</u>

a) When a lead nitrate solution is mixed with a potassium chromate solution, a yellow precipitate containing lead forms according to the equation:

Pb(NO_3)_2 (aq) + K_2CrO_4 (aq) → 2 KNO_3 (aq) + PbCrO_4(s).

b) Law of conservation of mass for the given reaction is true.

From the given table we know the mass of reactants and its products.

Law of conservation of mass is a principle when a reaction takes place in a closed system, the mass of the products and reactants in the system doesn't change.

⇒The sum of the mass of the reactants = The sum of the mass of the products.

The sum of the reactants = 128.71+128.97.

                                          = 257.68 g.

The sum of the products = 154.10+103.58.

                                          = 257.68 g.

Thus law of conservation of mass is true for the above reaction.

3 0
3 years ago
How many atoms are in 9.95 moles of iron?
zvonat [6]

Answer:

59.92 × 10²³ atoms are in 9.95 moles of iron

1.8 ×10²² molecules are in 0.03 moles of Carbon dioxide

1.19 moles are found in 7.20 x 10^23 atoms of platinum

6 0
3 years ago
Read the passage. Look at the underlined section marked number 9. There may be a mistake in the way the sentence is written. If
Alexus [3.1K]

The answer is D just did it

5 0
3 years ago
Read 2 more answers
If an atom has three shell and number of valence electrons are two. Is this element metal
cluponka [151]

Answer:

Metal

Element: Calcium

Valency: 2

Explanation:

To find the element, let's use the periodic table. (Look below)

We already went past 3 shells, just need the 2 electrons after it.

Just skip to the 4th row and count 2 to the right

We end up at Calcium.

Calcium is a metal and we're also on the alkaline earth metals column.

Calcium will need to lose 2 electrons to reach stability, so the valency is 2.

3 0
3 years ago
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