Matter & Mixtures — Set 2
Chemistry · पदार्थ और मिश्रण · Questions 11–20 of 50
Which of the following is a heterogeneous mixture?
Correct Answer: D. Oil and water
Oil and water form a heterogeneous mixture because they do not mix and form distinct layers. These components can be seen separately with the naked eye. Such mixtures do not have a uniform composition throughout their volume.
The fourth state of matter is generally considered to be?
Correct Answer: D. Plasma
Plasma is an ionized gas consisting of free electrons and ions. It is the most common state of matter in the universe, found in stars and lightning. It conducts electricity and is strongly influenced by magnetic fields.
Which technique is used to separate pigments from natural colors?
Correct Answer: B. Chromatography
Chromatography separates components based on their different rates of movement through a stationary phase. It is widely used in forensics and labs to identify complex mixtures. The word comes from the Greek 'chroma' meaning color.
At what temperature (in Celsius) does water have its maximum density?
Correct Answer: C. 4°C
Water reaches its maximum density at 4 degrees Celsius. Below this temperature, water expands and becomes less dense as it freezes. This unique property allows aquatic life to survive in frozen lakes.
A mixture of two liquids that do not dissolve in each other is called?
Correct Answer: B. Immiscible
Immiscible liquids like oil and water do not mix to form a single phase. They can be separated using a separating funnel based on their different densities. Miscible liquids, conversely, mix completely in all proportions.
Which of the following describes the Tyndall Effect?
Correct Answer: A. Scattering of light by particles
The Tyndall effect is the scattering of a beam of light by colloidal particles. This makes the path of light visible when passed through a colloid or a fine suspension. It is not observed in true solutions because the particles are too small.
What is the boiling point of water at standard sea-level pressure?
Correct Answer: A. 373 K
Water boils at 100 degrees Celsius, which is equivalent to 373 Kelvin. The conversion formula is Kelvin equals Celsius plus 273. Boiling point decreases as atmospheric pressure decreases at higher altitudes.
Which process is used to separate cream from milk?
Correct Answer: B. Centrifugation
Centrifugation uses rapid rotation to separate particles of different densities. The denser particles are forced to the bottom while lighter particles stay at the top. This method is also used in blood tests to separate plasma.
The smallest particle of an element that retains its chemical properties is?
Correct Answer: B. Atom
An atom is the basic building block of matter and the smallest unit of an element. It consists of a nucleus surrounded by electrons. Atoms of the same element are identical in their chemical nature.
Which of the following is an example of a physical change?
Correct Answer: A. Cutting paper
Cutting paper is a physical change because the chemical composition of the paper remains the same. Only the physical form or size of the substance is altered. Physical changes are generally reversible, though not always.