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3 years ago

TIME REMAINING

Chemistry

2 answers:

ArbitrLikvidat [17]3 years ago

6 0

A nail made from the metal iron.

Mazyrski [523]3 years ago

6 0

Answer: C. (A nail made from the metal iron).

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How much of strontium-90 will be left after 40 hours if you start with 960 grams and the half-life is 10 hours?

zmey [24]

Answer:

5 hours

Explanation:

7 0

2 years ago

6) How many valence electrons does an atom of Cu possess?

agasfer [191]

The answer is c)11 because copper has 11 valence electrons

7 0

3 years ago

If 842 grams of sodium hydroxide reacts with 750.0 grams of aluminum, how many grams of aluminum hydroxide should theoretically

Phantasy [73]

548.55 grams of aluminum hydroxide should theoretically form.

Explanation:

Balanced equation for the reaction:

3 NaOH + Al ⇒ Al(OH)3 +3 Na

DATA GIVEN:

mass of NaOH = 842 grams, atomic mass =39.9 grams/mole

mass of Al = 750 grams, atomic mass = 26.9 grams/mole

aluminum hydroxide theoretical yield = ?

Moles of NaOH reacted

number of moles = $\frac{mass}{atomic mass of 1 mole}$

putting the values in the equation

NaOH = $\frac{842}{39.9}$

= 21.1 MOLES OF NaOH

Al = $\frac{750}{26.9}$

= 27.8 moles

from the equation

from 3 moles of NaOH 1 mole of Al(OH)3 is produced

21.1 moles of NaOH will react to give x moles of Al(OH)3

$\frac{1}{3}$ = $\frac{x}{21.1}$

7.03 moles of Al(OH)3 is formed.

and

1 mole of Al(OH)3 is formed from 1 mole of Al in the reaction

so, 27.8 Moles will react to give give 27.8 moles of Al(OH)3 limiting reagent of the given reaction is NaOH

mass of Al(OH)3 =7.03 x 78 (atomic mass of Al(OH)3)

= 548.55 grams

theoretical yield from the given data is 548.55 grams

3 0

3 years ago

(1) The solubility of Salt AB2(S) IS 5mol/dm^3.

Svetlanka [38]

Answer:

a. Ksp = 4s³

b. 5.53 × 10⁴ mol³/dm⁹

Explanation:

a. Obtain an expression for the solubility product of AB2(S),in terms of s.

AB₂ dissociates to give

AB₂ ⇄ A²⁺ + 2B⁻

Since 1 mole of AB₂ gives 1 mole of A and 2 moles of B, we have the mole ratio as

AB₂ ⇄ A²⁺ + 2B⁻

1 : 1 : 2

Since the solubility of AB₂ is s, then the solubility of A is s and that of B is 2s

So, we have

AB₂ ⇄ A²⁺ + 2B⁻

[s] [s] [2s]

So, the solubility product Ksp = [A²⁺][B⁻]²

= (s)(2s)²

= s(4s²)

= 4s³

b. Calculate the Ksp of AB₂, given that solubility is 2.4 × 10³ mol/dm³

Given that the solubility of AB is 2.4 × 10³ mol/dm³ and the solubility product Ksp = [A²⁺][B⁻]² = 4s³ where s = solubility of AB = 2.4 × 10³ mol/dm³

Substituting the value of s into the equation, we have

Ksp = 4s³

= 4(2.4 × 10³ mol/dm³)³

= 4(13.824 × 10³ mol³/dm⁹)

= 55.296 × 10³ mol³/dm⁹

= 5.5296 × 10⁴ mol³/dm⁹

≅ 5.53 × 10⁴ mol³/dm⁹

Ksp = 5.53 × 10⁴ mol³/dm⁹

6 0

3 years ago

Scientist have genetically altered a common virus so that it can Destroy the most lethal type of brain tumor without harming the

sergey [27]

Answer:

The correct answer is - discovering or diagnosing the disease.

Explanation:

According to the question, this technology includes genetically modifying a common virus in order to destroy or kill the deadly brain tumor without affecting normal cells around the tumor, this technique is genetic engineering.

This technique can help in treating or curing the disease by killing the tumor cells and make them non-lethal. It can also prevent the tumor cells to grow and make them controlled. There is nothing mention related to diagnosing the disease in the question and it is not possible to find this tumor with help of such a technique.

3 0

3 years ago