(1) losing hydrogen
(2) synthetic indicator
(3) losing oxygen
(4) natural indicator
4. Answer any one of the following : 
About this paper
SSC Boards SCIENCE & TECHNOLOGY QUESTION PAPER FOR THE YEAR 2015.
This paper was mainly based on the contents of the Government prescribed textbook. It is very cleared from the paper that the textbook is a powerful instrument and source in science education and hence to use it effectively by the students is mandatory.
Most of the questions test the students 'knowledge and reasoning ability rather then their capacity in learning by heart. Therefore, students are supposed to know the lessons very well by understanding the terms, facts, concepts, activities, etc. from the textbook clearly.
In March, 2015 Question paper Chapters 4 , 13 had highest marks allotted. Majority of the questions asked were from the textbooks lessons rather than from the expected exercises in the textbook. Some of the questions were twisted or implicit which confused the students are found difficult to attempt. Hence, to attempt HOTS questions the student should be through with the concepts and activities given in the textbook. For objectives the students should prepare for all chapters.
Conclusion: SSC board papers for Science and Technology maintained good standards and students should be well prepared for attempting such papers.