Number of Nouns - Singular and Plural

Correct. The four words - leaf, life, knife, and self – follow the same rule while forming the plurals (change –f or –fe into –ves). Thus, the plural forms of these words are – leaves, lives, knives and selves. The word ‘roof’, though ending with –f, is an exception. The plural of roof is roofs.

Correct. The four words - cod, deer, moose, and bison – remain the same in the plural form too. The word ‘horse’ is the odd one here. The plural of horse is horses.

Correct. The four words - diagnosis, paralysis, axis, and emphasis– follow the same rule while forming the plurals (change –is into –es) Thus, the plural forms of these words are - diagnoses, paralyses, axes and emphases. The word ‘alibis’ is an odd one here since it is already in the plural form. The word ‘alibis’ is the plural of the noun – alibi.

Correct. The four words - foot, goose, tooth, and man – follow the same rule while forming the plurals (by changing the inside vowel/vowels of the words). Thus, the plural forms of these words are - feet, geese, teeth and men. The word ‘moon’ is an odd one here since it forms the plural by adding –s to the singular noun.

Correct. The four words - aquarium, medium, bacterium, and memorandum – follow the same rule while forming the plurals (by changing –um into –a). Thus, the correct plural forms of these words are - aquaria, media, bacteria and memoranda. (Though – aquariums, mediums and memorandums are also accepted.)The word ‘decorum’, though ending in –um, does not follow this rule of changing –um into -a. It forms the plural by adding –s.

Correct. The four words - potato, hero, mango, and volcano – follow the same rule while forming the plurals (by adding –es to the singular). (Rule: If the singular noun ends with –o and the –o has a consonant before it, add –es to form the plural of the word.) Thus, the plural forms of these words are - potatoes, heroes, mangoes and volcanoes. The word ‘memo’ is an odd one here since it is an exception to the rule and forms the plural by adding –s to the singular noun (memos).

Correct. The four words - oasis, analysis, basis, and crisis – follow the same rule while forming the plurals (by changing –is of the singular into -es). Thus, the plural forms of these words are - oases, analyses, bases and crises. The word ‘khakis’ is the odd one here since it is already in the plural form (khaki – khakis) and is not related to the rule mentioned above.

Correct. The four words - cactus, alumnus, hippopotamus, and syllabus– follow the same rule while forming the plurals (by changing –us of the singular into -i). Thus, the plural forms of these words are - cacti, alumni, hippopotami and syllabi. (Note: cactuses, hippopotamuses and syllabuses are also accepted.) The word ‘walrus’ is the odd one here since it forms the plural only by adding –es to the singular and is not related to the rule mentioned above.

Correct. The four words - offspring, aircraft, grapefruit, and salmon – remain the same in the plural form as well. The word ‘reflection’ is the odd one here since it forms the plural by adding –s to the singular noun (reflections).

Correct. The error is in part (b) of the sentence. The word ‘thesis’ needs to be in the plural form – theses.

Correct. The error is in part (a) of the sentence. The noun ‘oasis’ needs to be in the plural form (oases).

Correct. The four words - melody, territory, canopy, and army – follow the same rule while forming the plurals (by changing –y into –ies). (Rule: If the singular noun ends with -y and the -y has a consonant before it, change the -y into -ies to form the plural.) Thus, the plural forms of these words are – melodies, territories, canopies and armies. The word ‘valley’ is the odd one here since it ends with –y but has a vowel before the -y. In such a case, the plural is formed by simply adding –s to the singular noun.

Correct. The four words - attorney-at-law, runner-up, grant-in-aid, and mother-in-law – follow the same rule while forming the plurals (by adding –s to the first element of the hyphenated word). Thus, the plural forms of these words are – attorneys-at-law, runners-up, grants-in-aid and mothers-in-law. The word ‘get-together’ is the odd one here since it forms the plural by adding –s to the final element of the word (get-togethers).

Correct. Some words are used only in the plural form. Four of the given options fall under this category - scissors, mumps, spectacles, trousers. They are always used in the plural form. The odd one here is the word ‘cargoes’. It is the plural form of the noun – cargo.

Correct. The error is in part (c) of the sentence. Since the noun ‘performance’ is in the singular form, the word ‘criteria’ also needs to be in the singular form – (criterion).

Correct. The four words - half, shelf, wolf, and loaf – follow the same rule while forming the plurals (by changing the final letter –f into –ves). Thus, the plural forms of these words are – halves, shelves, wolves and loaves. The word ‘proof’, though ending with –f, is an exception. The plural of proof is proofs.

Correct. There are no errors in the sentence. All the nouns have been used in their correct number.

Correct. The four words - key, valley, storey, and monkey – follow the same rule while forming the plurals (by adding –s to the singular noun). (Rule: If the singular noun ends with -y and the -y has a vowel before it, simply add -s to form the plural.) Thus, the plural forms of these words are – keys, valleys, storeys and monkeys. The word ‘history’ is the odd one here since it ends with –y but has a consonant before the -y. In such a case, the plural is formed by changing –y into –ies (histories).

Correct. The words - bacteria, parentheses, nuclei, and criteria – are all in the correct plural form. The one with an error is the word – phenomenon. It is in the singular form. The plural form is phenomena.

Correct. Some words are used only in the plural form. Four of the given options fall under this category - oats, tweezers, measles, and headquarters. They are always used in the plural form. The odd one here is the word ‘taxes’. It is the plural form of the noun – tax.

Correct. The error is in part (a) of the sentence. The noun ‘diagnosis’ needs to be in the plural form (diagnoses).

Correct. The words - vertebrae, nuclei, analyses, and syllabi – are all in the correct plural form. The one with an error is the word – neurosis. It is in the singular form. The plural form of neurosis is neuroses.

Correct. The words - sons-in-law, heads-of-state, have-nots, and commanders-in-chief – are all in the correct plural form. The one with an error is the word – runner-ups. The first element of the hyphenated word (runner) should be pluralized. Thus, the plural form of runner-up is runners-up.

Correct. All the nouns in the sentence – data, teams, bases, and curricula - are in the plural form.

Correct. There are no errors in the sentence. All the nouns have been used in their correct number.

Correct. All the nouns in the sentence – symposia, synopses, strata and societies - are in the plural form in this option.

Correct. All the nouns in the sentence – commanders-in-chief, emphases, executions and plans - are in the correct plural form in this option.

Correct. The error is in part (a) of the sentence. The noun ‘crisis’ needs to be in the plural form (crises).

Correct. The words - dice, axes, ova, and automata – are all in the correct plural form. The one with an error is the word – stimulus. It is in the singular form. The plural form of stimulus is stimuli.

Correct. The plural noun with an error is the word – grant-in-aids. The correct form is grants-in-aid. The first element of the hyphenated word (grant) should be pluralized.