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vovikov84 [41]
3 years ago
11

If you purchased 2.31 μCi of sulfur-35, how many disintegrations per second does the sample undergo when it is brand new?

Chemistry
1 answer:
nikklg [1K]3 years ago
3 0

Answer:

8.547 x 10⁴disintegrations per second

Explanation:

To calculate the disintegrations per second as -

Given ,

2.31 μCi of sulfur  -35 .

Since ,

1 Ci = 3.7 * 10 ¹⁰ Bq

1 μCi = 10 ⁻⁶ Ci

Hence ,

conversation is done as follows -

2.31 ( 1 * 10⁻⁶) * ( 3.7 * 10¹⁰)

= 8.547 x 10⁴

Hence ,

8.547 x 10⁴disintegrations per second , the sample undergo for it to be brand new .

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Lapatulllka [165]

Clouds are xondense form of water vapour over dust particles present in the upper atmosphere.

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3 years ago
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Why is the energy supplied by the cooker greater than that calculated ?
TEA [102]

Answer:

Explanation:

Q1.

(a) 46 200

accept 46 000

allow 1 mark for correct substitution

ie 0.5 × 4200 × 22 provided no subsequent step

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(b) Energy is used to heat the kettle.

[3]

Q2.

(a) (approximate same size particles as each other and as liquid and gas) touching

do not accept particles that overlap

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an answer of 672 000 (J) scores 2 marks

[11]

Q3.

(a) x-axis labelled and suitable scale

Page 12 of 13

points plotted correctly

allow 5 correctly plotted for 2 marks, 3−4

correctly plotted for 1 mark

allow ± ½ square

2

line of best fit

(b)

allow ecf from line of best fit in part (a)

0.075 (°C/s)

an answer of 0.075 (°C/s) scores 2 marks

(c) Δθ = 11.5 (°C)

a calculation using an incorrect temperature

scores max 3 marks

ΔE = 1.50 × 900 × 11.5

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an answer of 15.525 (kJ) or 15.53 (kJ) or 15.5

(kJ) scores 4 marks

an answer of 15 525 (kJ) scores 3 marks

[10]

Q4.

(a) 80 °C

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an answer of 136 000 (J) scores 3 marks

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allow any correct description of wasted energy

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allow any sensible practical suggestion

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(d) efficiency = 300/500

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an answer of 0.6 or 60% scores 2 marks

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an answer of 0.6 with a unit scores 1 mark

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7 0
2 years ago
The primary method in which two connected objects transfer energy by heat flow is _____.
swat32
 Conduction is heat tranfer through physical contact. Hope this helps. :)
7 0
3 years ago
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Consider the following reaction: CO(g)+2H2(g)⇌CH3OH(g) This reaction is carried out at a different temperature with initial conc
Anni [7]

Answer:

Ka = 4.76108

Explanation:

  • CO(g) + 2H2(g) ↔ CH3OH(g)

∴ Keq = [CH3OH(g)] / [H2(g)]²[CO(g)]

                      [ ]initial         change         [ ]eq

CO(g)              0.27 M       0.27 - x        0.27 - x

H2(g)              0.49 M       0.49 - x        0.49 - x

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replacing in Ka:

⇒ Ka = ( x ) / (0.49 - x)²(0.27 - x)

⇒ Ka = (0.11) / (0.49 - 0.11)² (0.27 - 0.11)

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7 0
3 years ago
A student used 1.168g of an unknown weak acid and titrated it against 28.75 mL of 0.105M NaOH to reach the equivalence point. Wh
Vaselesa [24]

Answer:

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Explanation:

Step 1: Data given

Mass of the weak acid = 1.168 grams

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Since we only know 1 equivalence point, we suppose the acid is monoprotic

Step 2: Calculate moles NaOH

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Step 3: Calculate molar mass of weak acid

Molar mass = mass / moles

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Molar mass = 386.8 g/mol

The molar mass of the unknown acid is 386.8 g/mol

3 0
3 years ago
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