Matter & Mixtures — Set 4
Chemistry · पदार्थ और मिश्रण · Questions 31–40 of 50
What is the law that states mass is neither created nor destroyed in a chemical reaction?
Correct Answer: D. Law of Conservation of Mass
The Law of Conservation of Mass was proposed by Antoine Lavoisier. It states that the total mass of reactants equals the total mass of products. This principle is fundamental to balancing chemical equations.
Which of the following is a metalloid?
Correct Answer: D. Silicon
Silicon is a metalloid because it exhibits properties of both metals and non-metals. It is a semiconductor, making it vital for the electronics and computer industry. Metalloids are found along the zig-zag line on the periodic table.
Which of the following is the 'Gems' fact about Dry Ice?
Correct Answer: A. Solid carbon dioxide
Dry ice is the solid form of carbon dioxide and is known for not melting into a liquid. It undergoes sublimation directly into gas at room temperature. It is widely used as a cooling agent in food preservation.
The ratio by mass of hydrogen to oxygen in water is always?
Correct Answer: D. 1:8
According to the Law of Definite Proportions, water always contains hydrogen and oxygen in a 1:8 mass ratio. This ratio remains constant regardless of the source of the water. This law was formulated by Joseph Proust.
Which of these is the most common element in the Earth's crust?
Correct Answer: C. Oxygen
Oxygen is the most abundant element in the Earth's crust, making up nearly 46% of its mass. It primarily exists in the form of silicate minerals and oxides. Silicon is the second most abundant element.
What is the SI unit of temperature?
Correct Answer: D. Kelvin
Kelvin is the primary unit of temperature in the International System of Units (SI). It is an absolute scale where zero Kelvin represents the absence of all thermal energy. One Kelvin unit is equal in magnitude to one degree Celsius.
Which of the following is a characteristic of a chemical compound?
Correct Answer: A. It has a fixed melting point
A pure chemical compound has a sharp and constant melting point. This is because it has a uniform and fixed chemical composition throughout. Impurities would cause the melting point to vary or lower.
The amount of solute present in a given amount of solution is called its?
Correct Answer: D. Concentration
Concentration measures how much solute is dissolved in a specific volume of solvent or solution. It can be expressed in various ways like mass percentage or molarity. A concentrated solution has a relatively large amount of dissolved solute.
Which gas is used in the manufacture of soft drinks to provide fizz?
Correct Answer: D. Carbon dioxide
Carbon dioxide is dissolved under high pressure into soft drinks to create carbonation. When the bottle is opened, the pressure drops and the gas escapes as bubbles. This creates the characteristic 'fizz' and tangy taste.
Which of the following describes 'Brass'?
Correct Answer: C. A homogeneous mixture
Brass is an alloy consisting of copper and zinc, which are mixed at the atomic level. Because the components are uniformly distributed, it is classified as a homogeneous mixture. It is widely used for making musical instruments and decorative items.