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antiseptic1488 [7]
3 years ago
10

Which statement gives a reason why scientist think that the universe began with an explosion

Chemistry
1 answer:
yaroslaw [1]3 years ago
8 0

I believe the answer is

At the moment it is the best way of explaining our scientific knowledge.


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In the chemical equation below, name the reactant(s) and product(s).
Olenka [21]

Answer:Methane(CH4) and dioxygen(O2) are the reactants

Carbon dioxide(CO2) and water(H2O) are the products

Explanation:

4 0
2 years ago
N₂O(g) + 3 H₂(g) N₂H4(1) + H₂O(1) AH = -317 kJ/mol
docker41 [41]

Answer:

A

Explanation:

Recall that Δ<em>H</em> is the sum of the heats of formation of the products minus the heat of formation of the reactants multiplied by their respective coefficients. That is:


\displaystyle \Delta H^\circ_{rxn} = \sum \Delta H^\circ_{f} \left(\text{Products}\right) - \sum \Delta H^\circ_{f} \left(\text{Reactants}\right)

Therefore, from the chemical equation, we have that:


\displaystyle \begin{aligned} (-317\text{ kJ/mol}) = \left[\Delta H^\circ_f \text{ N$_2$H$_4$} +  \Delta H^\circ_f \text{ H$_2$O}  \right]   -\left[3 \Delta H^\circ_f \text{ H$_2$}+\Delta H^\circ_f \text{ N$_2$O}\right] \end{aligned}

Remember that the heat of formation of pure elements (e.g. H₂) are zero. Substitute in known values and solve for hydrazine:

\displaystyle \begin{aligned} (-317\text{ kJ/mol}) & = \left[ \Delta H^\circ _f \text{ N$_2$H$_4$} + (-285.8\text{ kJ/mol})\right] -\left[ 3(0) + (82.1\text{ kJ/mol})\right] \\ \\ \Delta H^\circ _f \text{ N$_2$H$_4$} & = (-317 + 285.8 + 82.1)\text{ kJ/mol} \\ \\ & = 50.9\text{ kJ/mol} \end{aligned}

In conclusion, our answer is A.

5 0
2 years ago
An atom of gold has a mass of 3.271 x 10-22g. How many atoms of gold are in 5.00g of gold?
rosijanka [135]
To get the number of gold atoms, you have to divide the mass of the gold by the mass of the gold atom. It follows this simple equation  \frac{mass of gold}{mass of gold atom}. 

Let x be the number of gold atoms. Plug in the values to a calculator.

x = \frac{5.00g}{3.271 x 10-22g}
Both have the same units so the unit gram(g) can be cancelled. 
x then would be equal to 1.53x10^22. So there are 1.53x10^22 atoms of gold in 5 g of gold
3 0
3 years ago
What is a substance?
ANTONII [103]
A is the answer im pretty sure
5 0
4 years ago
The cell theory states that all living things are composed of one or more cells that carry out the functions needed to support l
saw5 [17]

Answer:

New cells arise from existing cells.

Explanation:

According to the cell theory, "all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells"(Lumen Learning).

Cells are the basic unit of life. Some organisms consists of only one cell while other organisms have many cells and are called multicellular organisms.

In multicellular organisms, new cells are formed by the division of preexisting cells.

7 0
3 years ago
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