Among the following, pick the 'odd one out' with respect to the stated periodic property across Period 3 (from Na to Cl):

Non-metallic character increases

In the second period, the first ionisation enthalpy of boron is lower than that of beryllium. The correct reason is that:

the electron removed from boron is a $2p$ electron, while that from beryllium comes from a stable fully-filled $2s^2$ subshell

boron has a half-filled $2p^3$ configuration that resists electron removal

boron has a smaller atomic radius and a larger effective nuclear charge than beryllium

beryllium has more unpaired electrons, giving it extra exchange stability

Chapter testChemistryIncluded in the seriesTest 6 of 36

Bihar Board Class 11 Science Chemistry · Ch 3: Classification of Elements and Periodicity in Properties

Bihar Board Class 11 Science Chemistry · Ch 3: Classification of Elements and Periodicity in Properties is an online chapter test in the Bihar Board Class 11 Science pattern, covering Classification of Elements and Periodicity in Properties. Attempt it on SeatBeat with a timer like the real exam, then see a detailed solution for every question and your score and weak-topic analysis.

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Topic	Subject	Questions
Classification of Elements and Periodicity in Properties	Chemistry	30

Difficulty: 6 medium · 24 hard

Classification of Elements and Periodicity in Properties MCQ questions with answers

The first 3 of 30 questions. Unlock the series for the rest, each with a solution.

Q1. Among the following, pick the 'odd one out' with respect to the stated periodic property across Period 3 (from Na to Cl):
निम्नलिखित में से, आवर्त 3 (Na से Cl तक) में बताए गए आवर्ती गुण के संदर्भ में 'भिन्न विकल्प' चुनें:
- A. Ionisation enthalpy increases / आयनन एन्थैल्पी बढ़ती है
- B. Non-metallic character increases / अधात्विक गुण बढ़ता है
- C. Electronegativity increases / विद्युत्ऋणात्मकता बढ़ती है
- D. Atomic radius increases / परमाणु त्रिज्या बढ़ती है
Solution
Across a period, atomic radius and metallic character both decrease while ionisation enthalpy and electronegativity increase. 'Atomic radius increases' is the wrong trend, so it is the odd one out.
एक आवर्त में परमाणु त्रिज्या और धात्विक गुण दोनों घटते हैं जबकि आयनन एन्थैल्पी और विद्युत्ऋणात्मकता बढ़ती हैं। 'परमाणु त्रिज्या बढ़ती है' गलत प्रवृत्ति है, इसलिए यही भिन्न विकल्प है।
Q2. In the second period, the first ionisation enthalpy of boron is lower than that of beryllium. The correct reason is that:
दूसरे आवर्त में, बोरॉन की प्रथम आयनन एन्थैल्पी बेरिलियम की तुलना में कम होती है। इसका सही कारण यह है कि:
- A. boron has a half-filled $2p^3$ configuration that resists electron removal / बोरॉन में अर्धपूरित $2p^3$ विन्यास होता है जो इलेक्ट्रॉन निष्कासन का प्रतिरोध करता है
- B. boron has a smaller atomic radius and a larger effective nuclear charge than beryllium / बोरॉन की परमाणु त्रिज्या छोटी और प्रभावी नाभिकीय आवेश बेरिलियम से अधिक होता है
- C. the electron removed from boron is a $2p$ electron, while that from beryllium comes from a stable fully-filled $2s^2$ subshell / बोरॉन से निकाला गया इलेक्ट्रॉन एक $2p$ इलेक्ट्रॉन होता है, जबकि बेरिलियम से निकाला गया इलेक्ट्रॉन एक स्थिर पूर्णतः भरे $2s^2$ उपकोश से आता है
- D. beryllium has more unpaired electrons, giving it extra exchange stability / बेरिलियम में अधिक अयुग्मित इलेक्ट्रॉन होते हैं, जो इसे अतिरिक्त विनिमय स्थायित्व प्रदान करते हैं
Solution
Beryllium has a fully filled stable $2s^2$ configuration, while boron's single $2p$ electron is higher in energy and easier to remove. Hence boron has a lower first ionisation enthalpy despite its higher nuclear charge.
बेरिलियम का $2s^2$ विन्यास पूर्णतः भरा हुआ स्थिर होता है, जबकि बोरॉन का एकल $2p$ इलेक्ट्रॉन उच्च ऊर्जा पर होता है और निकालने में आसान होता है। इसलिए अपने अधिक नाभिकीय आवेश के बावजूद बोरॉन की प्रथम आयनन एन्थैल्पी कम होती है।
Q3. Match the oxide with its acid-base nature: (a) $Na_2O$ (b) $Al_2O_3$ (c) $Cl_2O_7$ (d) $CO$ (i) Amphoteric (ii) Neutral (iii) Basic (iv) Acidic Choose the correct matching.
ऑक्साइड का उसकी अम्ल-क्षार प्रकृति के साथ मिलान करें: (a) $Na_2O$ (b) $Al_2O_3$ (c) $Cl_2O_7$ (d) $CO$ (i) उभयधर्मी (ii) उदासीन (iii) क्षारीय (iv) अम्लीय सही मिलान चुनें।
- A. (a)-iii, (b)-ii, (c)-iv, (d)-i
- B. (a)-i, (b)-iii, (c)-ii, (d)-iv
- C. (a)-iii, (b)-i, (c)-iv, (d)-ii
- D. (a)-iv, (b)-i, (c)-iii, (d)-ii
Solution
Metallic $Na_2O$ is basic, $Al_2O_3$ is amphoteric, the highly non-metallic $Cl_2O_7$ is strongly acidic, and $CO$ is a neutral oxide. Acidic character of oxides increases across a period.
धात्विक $Na_2O$ क्षारीय है, $Al_2O_3$ उभयधर्मी है, अत्यधिक अधात्विक $Cl_2O_7$ प्रबल अम्लीय है, और $CO$ एक उदासीन ऑक्साइड है। एक आवर्त में ऑक्साइडों का अम्लीय गुण बढ़ता है।

Frequently asked questions

How many questions are in the Bihar Board Class 11 Science Chemistry · Ch 3: Classification of Elements and Periodicity in Properties?

30 questions for 30 marks, to be answered in 20 minutes.

Is there negative marking in the Bihar Board Class 11 Science Chemistry · Ch 3: Classification of Elements and Periodicity in Properties?

No — wrong answers are not penalised in this test.

Which topics does the Bihar Board Class 11 Science Chemistry · Ch 3: Classification of Elements and Periodicity in Properties cover?

Classification of Elements and Periodicity in Properties (30 questions).

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It is part of the BSEB Class 11 Science Test Series 2027 — Chapter-wise + Full Tests (36 tests, ₹149). You can first try Biology · Ch 1: The Living World for free.

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