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Gekata [30.6K]
2 years ago
13

PLEASE HELP!

Chemistry
2 answers:
fgiga [73]2 years ago
5 0
150/30 = 5
HF1 20/2 = 10
HF2 10/2 = 5
HF3 5/2 = 2.5
HF4 2.5/2 = 1.25
HF5 1.25/2 = 0.625
Answer: 0.63g
NikAS [45]2 years ago
4 0

Answer:  0,63 g

Explanation: During 150 days 5 decays happen. You can write a set

of masses : 20 g ⇒ 10 g after first decay, then 5 g , 2.5 g , 1,25 g

and after fifth decay 0.63 g

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Covalent bonded atoms make up what
White raven [17]
In a covalent bond, the atoms bond by sharing electrons. Covalent bonds usually occur between nonmetals. For example, in water (H2O) each hydrogen (H) and oxygen (O) share a pair of electrons to make a molecule of two hydrogen atoms single bonded to a single oxygen atom.
7 0
2 years ago
In what way are electrons quantized?
KiRa [710]

<u>Answer:</u> The correct option is A) They have fixed energy values.

<u>Explanation:</u>

Electron is one of the sub-atomic particle present around the nucleus of an atom which is negatively charged.

In an atomic model, it is assumed that the electron revolves around the nucleus in discrete orbits having fixed energy levels.

These electrons when jumping from one energy level to another, some amount of radiation is either emitted or absorbed.

These fixed energy levels are given by the Bohr model and thus, the electrons are quantized.

Hence, the correct option is A) They have fixed energy values.

6 0
3 years ago
Read 2 more answers
Draw the curved arrow mechanism for the reaction between (2S,3S)-3,5-dimethylhexan-2-ol and PCl3. Note the specific instructions
Vikki [24]

Answer:

(2R,3S)-2-chloro-3,5-dimethylhexane

Explanation:

As first step we have the <u>attack of the OH group</u> to the P atom in the PCl3 and one of the Cl atoms would leave. Then we will have a <u>rearrangement</u> to produce a <u>double bond </u>with the oyxgen on the OH. Finally the Cl produced will a<u>ttack the carbon</u> in a <u>Sn2 substitution reaction</u> to produce the halide with an <u>opposite configuration</u>.

4 0
3 years ago
You need to prepare 1 L of the citric acid/citrate buffer. You have chosen to use Method 1 (see lab presentation). Calculate the
prisoha [69]

Answer:

3.11 is the pH of the buffer

Explanation:

The pH of a buffer is obtained using H-H equation:

pH = pKa + log [Conjugate base] / [Weak acid]

<em>Where pH is the pH of the buffer, pKa = -log Ka = 3.14 for the citric buffer and [] could be taken as the moles of each species.</em>

The citric acid,HX (Weak acid), reacts with NaOH to produce sodium citrate, NaX (weak base) and water:

HX + NaOH → H2O + NaX

That means the moles of NaOH added = Moles of sodium citrate produced

And the resulitng moles of HX = Initial moles - Moles NaOH added

<em>Moles HX and NaX:</em>

Moles NaOH = 0.100L * (0.65mol / L) = 0.065 moles NaOH = Moles NaX

Moles HX = 0.300L * (0.45mol / L) = 0.135 moles HX - 0.065 moles NaOH = 0.070 moles HX

Replacing in H-H equation:

pH = 3.14 + log [0.065mol] / [0.070mol]

pH = 3.11 is the pH of the buffer

8 0
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Ber [7]
Sc(21), Cr(24), Fe(26), Zn(30)
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