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oee [108]
3 years ago
13

Giselle is working with a chemical substance in a laboratory. She observes that when the chemical is heated, it gives off a gas.

She assumes that the gas is oxygen but decides to test this assumption to verify it. Which type of scientific knowledge is Giselle’s assumption? A. fact B. hypothesis C. law D. observation E. theory
Chemistry
1 answer:
Helga [31]3 years ago
5 0

Answer:

The correct answer is B. Hypothesis

Explanation:

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A substance that contains only one type of particle is an __________​
Dvinal [7]

the answer is a chemical element

7 0
3 years ago
Read 2 more answers
The isomerization of methylisonitrile to acetonitrile (CH3NC(g) ???? CH3CN) is first order in CH3NC. The rate constant for the r
Hoochie [10]

Answer:

The half life is     H_{1/2}= 7333.3sec

Explanation:

   The half life of a first order  reaction is mathematically represented as

                          H_{1/2} = \frac{0.693}{Rate Constant }

 Substituting   9.45 * 10^{-5}s^{-1}  for the rate constant

                         H_{1/2} = \frac{0.693}{9.45*10^{-5}}

                                 H_{1/2}= 7333.3sec

5 0
3 years ago
Q2.  0.254 g of KHP (204 g/mol) titrated against 20.0 mL of unknown NaOH (40.0 g/mol) solution to get the end point of phenolpht
Vera_Pavlovna [14]

Answer:

<u>Mass concentration (g/L) </u><u><em>= 2.49g/L.</em></u>

Explanation:

No. of moles = \frac{mass}{molar mass}

= \frac{0.254}{204} = 0.001245 moles

Concentration of KHP (C1) in litres = n/v

= \frac{0.001245}{0.02} = 0.062 mol/L

We know that:

C_{1} V_{1} = C_{2} V_{2}

where c1v1 and c2v2 are the products of concentration and volumes of KHP and NaOH respectively.

Since mole ratio is 1 : 1.

1 mole of NaOH - 40g

0.001245 mole of NaOH = 40 × 0.001245 = 0.0498g

⇒0.0498g of NaOH was used during the titration

<u><em>∴Mass concentration (g/L) = 0.0498g ÷ 0.02L</em></u>

<u><em>= 2.49g/L.</em></u>

3 0
3 years ago
how many moles of sodium hydroxide (NaOH) are required to completely neutralize 2 mol of nitric acid (HNO3)
Brut [27]

2 moles of sodium hydroxide will be needed.

<h3><u>Explanation</u>:</h3>

Sodium hydroxide is a compound which is a base and nitric acid is the acid. The formula of the nitric acid is HNO3 and that of sodium hydroxide is NaOH.

The reaction between them are

NaOH +HNO3 =NaNO3 +H2O.

So here we can see that 1 mole of sodium hydroxide reacts with 1 mole of nitric acid to produce 1 mole of sodium nitrate and 1 mole of water.

So for 2 moles of nitric acid, 2 moles of sodium hydroxide will be required.

6 0
3 years ago
Which of the subshells below do not exist due to the constraints upon the angular momentum quantum number?A) 2dB) 2sC) 2pD) all
Gnom [1K]

Answer:

  • Option A): <em>Due to the constraints upton the angular momentum quantum number, the subshell </em><u><em>2d</em></u><em> does not exist.</em>

Explanation:

The <em>angular momentum quantum number</em>, identified with the letter l (lowercase L),  number is the second quantum number.

This number identifies the shape of the orbital or <em>kind of subshell</em>.

The possible values of the angular momentum quantum number, l, are constrained by the value of the principal quantum number n: l can take values from 0 to n - 1.

So, you can use this guide:

Principal quantum   Angular momentum         Shape of the orbital

number, n                 quantum number, l

         1                                      0                             s

         2                                     0, 1                          s, p

         3                                     0, 1, 2                      s, p, d

Hence,

  • <u>the subshell 2d (n = 2, l = 2) is not feasible</u>.

  • 2s (option B) is possible: n = 2, l = 0

  • 2p (option C) is possible: n = 2, l = 1

7 0
4 years ago
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