Most naphthalene is derived from coal tar. Typical coal tar is about 10% naphthalene by weight. Naphthalene in crystallized from coal tar fraction with boiling point 210-220°C than it is washed with sulphuric acid solution to remove theophany, with diluted alkali to remove phenol and, finally, is distilled. Also naphthalene is produced from heavy petroleum fractions during petroleum refining, but today petroleum-derived naphthalene represents only a minor component of production . Coal tar is brown or black liquid of extremely high viscosity. In the coal gas era, there were many companies in Britain whose business was distil coal tar to separate the higher-value fractions, such as naphtha, creosote and pitch.
ए, ऐ, ओ, औ कौन सा स्वर है ?
निम्नलिखित में से कौन.वर्ण अन्तःस्थ नहीं है?
इनमे से कर्मवाच्य किस वाक्य में है ?
मात्राएँ कितने प्रकार के होते है ?
भानुफल किसका पर्याय है?
कौन सा कथन सही नहीं हैं ?
किस वाक्ये में भववाच्य का प्रयोग हुआ है ?
'आंखों का तारा होना मुहावरे का सही अर्थ क्या है
' उँगली पर नाचना ' मुहावरे का सही अर्थ है :
निम्नलिखित विलोमार्थी शब्द - युग्मों में असंगत है :
