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To determine the correct conditions, we use the Combined Gas Law, which relates the pressure, volume, and temperature of a fixed amount of gas: \(\frac{P\(_1\)V\(_1\)}{T\(_1\)}\) = \(\frac{P\(_2\)V\(_2\)}{T\(_2\)}\) Given: V\(_1\) = 400 cm\(^3\) , T\(_1\) = 400 K , P\(_1\) = 1 atm V\(_2\) = 200 cm\(^3\) , T\(_2\) = ? , P\(_2\) = ? We need to find which pair of pressure and temperature satisfies the equality P\(_1\)V\(_1\)/T\(_1\) = P\(_2\)V\(_2\)/T\(_2\) First, calculate the initial constant: \(\frac{1 atm . 400cm{^3}}{400K}\) = 1 Now, test Option C: P\(_2\) = 1 atm V\(_2\) = 200cm\(^3\) T\(_2\) = 200 K \(\frac{1 atm . 200cm{^3}}{200K}\) = 1 Options A, B and D will not give you 1.

The nucleus of an ordinary hydrogen atom (specifically the most abundant isotope, protium) consists of a single proton. Atomic Number: Hydrogen has an atomic number of 1, meaning it contains exactly one proton.

Acidified potassium dichromate (K\(_2\)Cr\(_2\)O\(_7\)) is a strong oxidizing agent that undergoes a distinct colour change during redox reactions. In an acidic medium, the chromium is present in the dichromate ion (Cr\(_2\)O\(_7\)\(^{2-}\)), where it has an oxidation state of +6. This ion gives the solution its characteristic orange colour. When it acts as an oxidizing agent, it accepts electrons and is reduced to chromium(III) ions (Cr\(^{3+}\)), where the oxidation state is +3. The formation of Cr\(^{3+}\) ions (often as chromium(III) sulfate in sulphuric acid solutions) turns the solution green.

While standard chemical definitions usually limit metalloids to a list of six elements (Boron, Silicon, Germanium, Arsenic, Antimony, and Tellurium), Selenium is frequently classified as a metalloid in various educational contexts and standardized tests because it exhibits intermediate properties between metals and nonmetals. Though more strictly defined as a nonmetal in some academic circles, it is the only viable answer among the choices provided that displays "metalloid-like" or semiconducting behavior.

Iodine can be separated from calcium chloride using sublimation because of the distinct physical properties of the two substances: 1. Iodine is a sublimable solid, meaning it transitions directly from a solid state to a gaseous state upon heating without passing through a liquid phase. 2. Calcium chloride is a non-sublimable ionic salt with a very high melting point, so it remains in the solid state while the iodine vapourizes.

Sodium chloride (common salt) is a versatile chemical used in various industrial and domestic processes. While it has many applications, it is not typically used for the primary treatment of water (such as purification or filtration of polluted water).

A metallic bond is an intramolecular (chemical) bond rather than an intermolecular force. It involves a lattice of metal cations surrounded by a "sea" of delocalized valence electrons. Because this bond exists within a substance to hold its atoms together rather than between discrete molecules, it does not qualify as an intermolecular force.

NO\(_2\) (nitrogen dioxide) is a covalent compound, not an ionic one. It is formed by the sharing of electrons between two non-metals: nitrogen and oxygen. Unlike ionic compounds, which typically involve the transfer of electrons from a metal to a non-metal, NO\(_2\) consists solely of non-metallic elements that form molecular bonds.

Sodium carbonate (Na\(_2\)CO\(_3\)) is an alkali metal carbonate that is extremely stable and does not decompose when heated strongly, even at Bunsen burner temperatures. This stability is due to the large size and low charge density of the sodium cation (Na\(^+\)), which has low polarizing power and cannot easily distort the carbonate ion (CO\(_3\)\(^{2-}\)) to break its carbon-oxygen bonds. Most group 1 carbonates (except lithium carbonate) exhibit this high thermal stability.

A universal indicator changes colour to represent the pH level of a substance. For instance, a red colour indicates a very low pH (typically 0 to 3), which corresponds to a strong or concentrated acid; for pH 0: Specifically produces a strong red or dark red colour, representing the highest acidity and for indicator Spectrum: the colour moves from red (strong acid) to orange/yellow (weak/dilute acid), green (neutral), and finally blue/purple (bases).

Nitrogen dioxide (NO\(_2\)) is unique because it undergoes a disproportionation reaction when dissolved in water. In this reaction, the nitrogen atom (which has an oxidation state of +4 in NO\(_2\) ) is both oxidized and reduced simultaneously, resulting in the formation of two distinct acids; 2NO\(_2\) + H\(_2\)O → HNO\(_2\) + HNO\(_3\)

Ethanol (C\(_2\)H\(_5\)OH) can be prepared in the laboratory by the hydration of ethene (C\(_2\)H\(_4\)). This process involves an acid-catalyzed addition reaction where water (in the form of steam) is added across the double bond of ethene in the presence of a concentrated acid catalyst, such as phosphoric(V) acid (H\(_3\)PO\(_4\)) or sulphuric acid (H\(_2\)SO\(_4\)).

Alkali metals (Group 1 elements) have a single valence electron in their outermost shell. In a metallic lattice, these valence electrons are weakly held by the nucleus and become delocalised, meaning they are free to move throughout the entire structure.

In a chemical reaction, \DeltaH(change in enthalpy) is positive when the reaction is endothermic, meaning the system absorbs heat from its surroundings. i.e \DeltaH\(_{product}\) must be greater than \DeltaH\(_{reactant}\).

Propene (C\(_3\)H\(_6\)) is an alkene that contains one carbon-carbon double bond (C=C) and one carbon-carbon single bond (C-C). According to bonding rules: A single bond consists of exactly one sigma (σ) bond. A double bond consists of one sigma (σ) bond and one pi (\pi) bond. Because propene has only one double bond in its structure (CH\(_2\)=CH-CH\(_3\)), it contains exactly one pi bond.