What is the role of a control group in any experiment

Controlled group does not receive the treatment.  It used as a benchmark to measure how different tested subjects affected the result of the experiment.

For example, the famous experiment of whether plants grow faster with music in one room and without music in the other room. The plant in the no music room is the controlled group.

there is no stairs in bungalow

explanation:

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water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.