What is the standard unit that astronomers use to measure the size of a star

True or false When heat flows to an object, it can change states.

emmasim [6.3K]

Answer: True

Explanation:

The matter exists as solid, liquid or gas. These are called the states of matter. The change of matter from one state to another can be achieved by heating or cooling.

The solid state can be converted into liquid state by providing heat to solid. The heat will make the particles move farther, resulting into liquid state.

Similarly when liquid state is provided heat, it changes to gaseous state. The heat will make the particles move much more faster.

Thus the statement that when heat flows to an object, it can change states is True.

7 0

3 years ago

An element has two naturally-occurring isotopes. The mass numbers of these isotopes are 113 amu and 115 amu, with natural abunda

DENIUS [597]

Answer: Its average atomic mass is 114.9 amu

Explanation:

Mass of isotope 1 = 113 amu

% abundance of isotope 1 = 5% = $\frac{5}{100}=0.05$

Mass of isotope 2 = 115 amu

% abundance of isotope 2 = 95% = $\frac{95}{100}=0.95$

Formula used for average atomic mass of an element :

$\text{ Average atomic mass of an element}=\sum(\text{atomic mass of an isotopes}\times {{\text { fractional abundance}})$

$A=\sum[(113\times 0.05)+(115\times 0.95)]$

$A=114.9amu$

Thus its average atomic mass is 114.9 amu

5 0

3 years ago

Many oxidation-reduction reactions can be balanced by inspection. Try to balance the following reactions by inspection. In each

Phoenix [80]

Answer:

Balanced reaction: C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)

Reduced: O₂

Oxidized : C₃H₈

Explanation:

For the given reaction:

C₃H₈(g) + O₂(g) → CO₂(g) + H₂O(l)

In the reactants, there are 3 C, and in the products only one, so we multiply CO₂ by 3:

C₃H₈(g) + O₂(g) → 3CO₂(g) + H₂O(l)

In the reactants, there are 8 H, and in the products, there are 2 H, so we multiply H₂O by 4:

C₃H₈(g) + O₂(g) → 3CO₂(g) + 4H₂O(l)

In the reactants are 2 O, and in the products 10 O, so we multiply O₂ by 5:

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)

The reaction is balanced.

Let's identify the oxidation number (Nox) of the elements in each compound.

C₃H₈:

H has fix Nox equal to +1, and the molecule is neutral, so, calling x the Nox of C:

3x + 8 = 0

3x = -8

x = -8/3

O₂:

Because is a pure compound, the Nox of O is 0.

CO₂:

The Nox of O is fix equal to -2, and the molecule is neutral, so, calling x the Nox of C:

2x -4 = 0

2x = 4

x = +2

H₂O:

The Nox of H and O are fixed, respectively, +1 and -2.

So, the carbon in C₃H₈ is oxidized because its Nox is increasing, and oxygen in O₂ is reduced because its Nox is decreasing.

6 0

3 years ago

when 0.15 moles of sodium reacts with 0.30 moles of oxygen what is the moles of the product formed when one reagents is used in

Mamont248 [21]

Answer:

0.075 moles of product formed.

Explanation:

Given data:

Number of moles of oxygen = 0.30 mol

Number of moles of oxygen = 0.15 mol

Number of moles of product formed = ?

Solution:

Chemical equation:

4Na + O₂ → 2Na₂O

Now we will compare the moles of Na₂O with oxygen and sodium.

Na : Na₂O

4 : 2

0.15 : 2/4×0.15 = 0.075 mol

O₂ : Na₂O

1 : 2

0.30 : 2/1×0.30 = 0.6 mol

Less number of moles of Na₂O are produced by sodium thus it will limit the yield of Na₂O and act as limiting reactant while oxygen is in excess.

3 0

3 years ago

Use the picture of the heliocentric and geocentric models to answer the question below:

xxMikexx [17]

Answer:

Model 1 represents the old geocentric model of the solar system and Model 2 represents the newer heliocentric model of the solar system.

Explanation:

Model 1 has earth in the center, therefore it is geocentric. the geocentric model of the solar system is old. Nobody believes in it anymore because it is scientifically inaccurate.

Model 2 has the sun in the center, therefore it is heliocentric. This is the newer model of the solar system.

6 0

2 years ago