Answer: Option (D) is the correct answer.
Explanation:
- A pure substance is defined as the substance that is made up of only one type of atom or only one type of molecule.
For example, 
is a molecule and it is a pure substance.
Also, substances that contain two or more different element which are chemically combined in a fixed ratio by mass are known as compounds. They are also pure substances.
A pure substance can only be separated by a chemical method and not by any physical method.
- A heterogeneous mixture is defined as the mixture which contains non-uniform composition of solute particles into the solution.
For example, mud dissolved in water.
It is not necessary that two or more substance present in a heterogeneous mixture should be of same phase.
Also, it is not necessary that combination of a liquid and a solid always results in a heterogeneous mixture.
If the solid is able to dissolve completely into the liquid then it will result in a homogeneous mixture.
- Whereas a homogeneous mixture is defined as the mixture which contains uniform distribution of solute particles into the solvent.
For example, salt dissolved in water is a homogeneous mixture.
Thus, we can conclude that the statement composition is uniform throughout a homogeneous mixture, is correct.
Answer:
In case of low-mass stars,the outer layers of the low mass stars are expelled as the core collapses such that the outer layers form a planetary nebula.
Explanation:
In case of low-mass stars,the outer layers of the low mass stars are expelled as the core collapses such that the outer layers form a planetary nebula. The core remains as a white dwarf and finally become a black dwarf as it cools down. A low mass star consumes its core hydrogen and turns it into helium over its lifetime.
Answer:
Initial pressure = 157 kpa (Approx)
Explanation:
Given:
final temperature = 234 K
final pressure = 210 kpa
Initial temperature = 175 K
Find:
Initial pressure
Computation:
Initial pressure / Initial temperature = final pressure / final temperature
Initial pressure / 175 = 210 / 234
Initial pressure = 157 kpa (Approx)
Answer: Read Explanation
Explanation: Index fossils are useful because they tell the relative ages of the rock layers in which they occur. Geologists use particular types of organisms, such as trilobites, as index fossils.
Answer:
1.87x10⁻³ M SO₄²⁻
Explanation:
The reaction of SO₄²⁻ with Ba²⁺ (From Ba(NO₃)₂) is:
SO₄²⁻(aq) + Ba²⁺(aq) → BaSO₄(s)
<em>Where 1 mole of SO₄²⁻ reacts per mole of Ba²⁺</em>
<em />
To reach the end point in this titration, we need to add the same moles of Ba²⁺ that the moles that are of SO₄²⁻.
Thus, to find molarity of SO₄²⁻ we need to find first the moles of Ba²⁺ added (That will be the same of SO₄²⁻). And as the volume of the initial sample was 100mL we can find molarity (As ratio of moles of SO₄²⁻ per liter of solution).
<em>Moles Ba²⁺:</em>
7.48mL = 7.48x10⁻³L ₓ (0.0250moles / L) = 1.87x10⁻⁴ moles of Ba²⁺ = Moles of SO₄²⁻
<em>Molarity SO₄²⁻:</em>
As there are 1.87x10⁻⁴ moles of SO₄²⁻ in 100mL = 0.1L, molarity is:
1.87x10⁻⁴ moles of SO₄²⁻ / 0.1L =
<h3> 1.87x10⁻³ M SO₄²⁻</h3>
