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irinina [24]
4 years ago
9

How many electrons are there in the only energy level of helium, a noble gas? * Two Three Six Eight​

Chemistry
1 answer:
Lera25 [3.4K]4 years ago
6 0

Answer:

Explanation:

Noble gases are the least reactive of all known elements. That's because with eight valence electrons, their outer energy levels are full. The only exception is helium, which has just two electrons.

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Name the following compound: <br> C5Si7
skad [1K]

Answer:

Pentacarbon heptasilicide.

Explanation:

In order to name the following compound, we need to identify whether it is molecular or ionic.

Molecular compounds consist of non-metal atoms, while ionic compounds would have metal cations in their composition.

In the given compound, C_5Si_7, we have two non-metals, carbon and silicon, meaning we should follow the molecular compound naming rules. The rules involve using prefixes to state the number of individual atoms.

The two prefixes required here are 'penta' for 'five' to indicate 5 carbon atoms present and 'hepta' for 'seven' to indicate 7 silicon atoms present.

The first part of the name would be pentacarbon (notice that the standard name for the first element is used). The second part would be heptasilicide (notice that the second atom would have an ending of -ide followed by the standard beginning of silicon).

4 0
3 years ago
Mg(s) + ½O2(g) → MgO(s) + 146 kcal/mole H2(g) + ½O2(g) → H2O(g), ΔH = -57.82 kcal/mole What type of reaction is represented by t
professor190 [17]
Answer is: both reactions are exothermic.
<span>
In exothermic reactions, heat is released and enthalpy of reaction is less than zero (as it show second chemical reaction).
According to Le Chatelier's principle when the reaction is exothermic heat is included as a product (as it show first chemical reaction).</span>
4 0
3 years ago
Two moles of magnesium (Mg) and five moles of oxygen (O2) are placed in a reaction vessel. When magnesium is ignited, it reacts
Y_Kistochka [10]

Answer:

Explanation:

Two moles of magnesium (Mg) and five moles of oxygen (O2) are placed in a reaction vessel. When magnesium is ignited, it reacts with oxygen. What is the limiting reactant in this experiment?

Mg + O2 → MgO (unbalanced)

first, balance the equation

2Mg +O2-------> 2MgO

two magnesium atoms react with one diatomic oxygen molecule

there is a 1:1 ratio of magnesium to oxygen atoms

but we have 2 moles of magnesium atoms and 2X5 = 10 moles of oxygen atoms

the lesser magnesium LIMITS the amount of product we can make, so it is the LIMITING REAGENT.

6 0
3 years ago
If a balloon initially has a volume of 4.0 liters and a temperature of 10 degrees Celsius, what will the volume of the balloon b
Anika [276]
The answer is D. 8.1L
7 0
3 years ago
3. How many moles in 28 grams of CO2?
Burka [1]

Answer:

0.636 moles

Explanation:

6 0
3 years ago
Read 2 more answers
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