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Assoli18 [71]
3 years ago
11

*40 IF YOU ANSWER CORRECTLY & ADDED BRAINIEST*

Chemistry
1 answer:
Vikentia [17]3 years ago
6 0

Answer:

1. B

2. C

Explanation:

1. There are 15 electrons which means that the element is phosphorus. We know it is in the excited state because an electron from the second ring has moved to the third one, typically it would be 2 - 8 - 5.

2. An element with 3 valence electrons will be 3 spaces from the left side of the periodic table. Sodium is 1, Magnesium is 2, Aluminium is 3, and Silicon is 4. Noble gasses on the right have all 8.

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A certain object has a volume of 25.0 ml and a mass of 100 g. what is the density of the object
Tpy6a [65]
Density= mass/volume

             = 100/25
density  = 4g/ml
8 0
3 years ago
Can someone help me please I will mark you brainliest
lara [203]

1: a, 2:a, 3:a, 4:c, 5:d, 6:d, 7:c;

4 0
2 years ago
HELP!! BEST ANSWER GETS BRAINLIEST!!
vampirchik [111]
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3 years ago
Which of the following acts as a catalyst in catalytic converters?
Serhud [2]

Answer:

B. Metal

Explanation:

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Hope it helps plz mark brainlist :)

5 0
3 years ago
Read 2 more answers
One of relatively few reactions that takes place directly between two solids at room temperature is <img src="https://tex.z-dn.n
kolbaska11 [484]

Answer:

a) Ba(OH)₂.8H₂O(s) + <em>2 </em>NH₄SCN(s) → Ba(SCN)₂(s) +<em>10</em> H₂O(l) + <em>2</em> NH₃(g)

b) 3.14g must be added

Explanation:

a) For the reaction:

Ba(OH)₂.8H₂O(s) + NH₄SCN(s) → Ba(SCN)₂(s) + H₂O(l) + NH₃(g)

As you see, there are 8 moles of water in reactants and 2 moles of oxygen in octahydrate, thus, water moles must be 10:

Ba(OH)₂.8H₂O(s) + NH₄SCN(s) → Ba(SCN)₂(s) +<em>10</em> H₂O(l) + NH₃(g)

To balance hydrogens, the other coefficients are:

Ba(OH)₂.8H₂O(s) + <em>2 </em>NH₄SCN(s) → Ba(SCN)₂(s) +<em>10</em> H₂O(l) + <em>2</em> NH₃(g)

b) As you see in the balanced reaction, 1 mole of barium hydroxide octahydrate reacts with 2 moles of NH₄SCN. 6.5g of Ba(OH)₂.8H₂O are:

6.5 g × (1mol / 315.48g) =<em> 0.0206moles of  Ba(OH)₂.8H₂O</em>. Thus, moles of NH₄SCN that must be used for a complete reaction are:

0.0206moles of  Ba(OH)₂.8H₂O × ( 2 mol NH₄SCN / 1 mol Ba(OH)₂.8H₂O) = <em>0.0412moles of NH₄SCN</em>. In grams:

0.0412moles of NH₄SCN × ( 76.12g / 1mol) = <em>3.14g must be added</em>

8 0
3 years ago
Read 2 more answers
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