बिटुमेन (Bitumen) निम्नलिखित में से किस विलायक में पूरी तरह से घुलनशील होता है?

According to Indian standard bitumen grading (IS 73), lower penetration numbers indicate harder bitumen grade. Which of the following bitumen grades is the hardest?

Which of the following grades of bitumen is the hardest?

In a standard bitumen penetration test, the minimum distance between two test points (or samples) should be __________