Download App

Periodic Classification of Elements — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10SciencePeriodic Classification of Elements3 Marks
Question
The atomic number of an element is 20.
  1. Write its electronic configuration and determine its valency.
  2. Is it a metal or a non-metal?
  3. Write the formula of its chloride.
  4. Is it more reactive or less reactive than Mg (atomic number 12)? Give reason for your answer.
✓

Answer

a. $X_{(20)}-2,8,8,2$.
Valence electrons-2.
Hence valency is 2 .
b. It is a metal.
c. $XCl _2$
d. It is more reactive than Mg as reactivity increases down the group.
Mg- III Period.
And $X_{20}( Ca )$ - IV Period.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "[3 Mark Questions]" from Periodic Classification of Elements→Periodic Classification of Elements — all question types→Science STD 10 question papers→CBSE Board STD 10 question papers→CBSE Board question paper generator→

Similar questions

What is the difference between a cation and an anion? How are they formed? Give the names and symbols of one cation and one anion.
→
How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?
→
What is meant by a primary consumer, secondary consumer and a tertiary consumer? Give one example of each.
→
Calculate the area of cross-section of a wire if its length is 1.0m, its resistance is $23 Ω$ and the resistivity of the material of the wire is $1.84\times10 Ω\ \text{m}.$
→
What is speciation? List four factors responsible for speciation.
→
Give one example to show how the endocrine system coordinates our body activities.
→
Write one main difference between asexual and sexual mode of reproduction. Which species is likely to have comparatively better chances of survival – the one reproducing asexually or the one reproducing sexually? Give reason to justify your answer.
→
Explain the term "Regeneration" as used in relation to reproduction of organisms. Describe briefly how regeneration is carried out in multicellular organisms like Hydra.
→
What is a solar cell? Draw the labelled diagram of a solar cell.
→
What do you understand by the term “electromagnetic induction”? Explain with the help of a diagram.
→